Yes.
TLDR - Prevented nuclear war - worth every cent!
Alright so a lot of this is misunderstanding of the historical contexts (or conflation of historical perceptions with actual reality) that we have better info on since the 1990's. Allow me to explain, or you can scroll down to the TL;DR if you don't want to read it all.
Leaving aside the fact that "nothing" is just as viable an alternative as anything of the offered (and would be ideal, given how close B-1B and AGM-129 coincide in time), both blocs in the Cold War were inherently defensive in nature. Soviet war plans anticipated a surprise NATO attack hiding in a REFORGER exercise, in a similar fashion to NATO war plans anticipating an attack under the guise of a Zapad exercise, and the Soviets were about as interested in pursuing nuclear war as a matter of civilian policy as the US was, which means explaining the Cold War as some titanic struggle against the two superpowers and not simply two big countries disagreeing over their proxies and misinterpreting the other as being prepared for war like "the last guys" shaky at best.
Deterrence doesn't work if neither side is interested in starting a fight, because there's nothing to deter. This is the Cold War. It's highly debatable whether it functions if both sides are willing to poke and prod the other, either, and doesn't just make oblique strategies more effective (that is, if you consider the Marshal Plan as an act of economic warfare). This is the current era. The Red Army just planned to survive an atomic war, should America start one, which I suppose would be easy to misinterpret as aggression, and was something the West couldn't do because having redundant industrial centers and highly militarized economies are bad for business (literally).
The entire thing was a misunderstanding and misinterpretation of what to do over Germany, which persisted right up to German reunification in 1990, with Margaret Thatcher being opposed to it because she was afraid of the same thing the Soviets were: that the Germans were going to start another world war. Eventually. It was one of the major reasons she split from the Tories and Major became PM, IIRC.
It feels a bit quaint nowadays but a lot of the Soviet leadership right up to the end were old fogies who fought the Germans in the Great Patriotic War. It was a much greater issue in 1948 when the United States and British Empire decided to recreate a unified German state instead of dismantling it outright as the French (to an extent) and the Soviets very muchly wanted. Since the single crux of the issue was "what do we do with Germany", because the Soviets had given up on expanding their reach beyond their immediate borders militarily after the Miracle on the Vistula, there was no serious argument that they would start an offensive war. The Warsaw Pact, Afghanistan, China, Yugoslavia, Albania: these were the prime Soviet enemies (notice how they are all buffer states or "fellow" communists and not places like France, Italy, or America), and China is a bit wiffly since the Red Army didn't launch some massive multi-army mechanized counter attack to retake the Amur River islands when Mao stole them. It just declared a ceasefire and let the diplomats handle it because if we go to war with China, the US might attack it in Europe. Japan and Korea were a distant second concern, as should the US decide to invade (the USSR was just as concerned as MacArthur was about Korea, in reality, but also less trigger happy due to having fewer atom bombs and bombers) through these countries then the Far East Theater would be kinda chewed up and spat out.
This was only unknown at the time since the Soviets were pretty mum about everything from how many nuclear warheads they had in their silos to how many teaspoons of baking soda to use in babushka's rye bread recipe, for a lot of different reasons ranging from the practical to the petty. Had the extent of the misunderstandings been known to both sides, the arms races would have been a lot less dramatic and militaries would have pared down their sizes much faster than they did IRL. Those monies would probably have gone to infrastructure or something more useful.
With the benefit of hindsight, we know that B-1B was dopey from the start, simply because it doesn't even retain its nuclear attack role, and basically exists to be a more expensive B-52H or F-15E (i.e. a conventional bomb truck). With the foggy gaze of foresight, we know that ATB existed, which promised to be the regional bomber par excellence, and B-1B was considered (rightfully) redundant, along with the F-111 it was supposed to replace. So even on a technical level while it's nothing more than a fat F-15E, it still constitutes the most expensive aircraft in AFGSC's inventory. B-52H can use all its weapons (and a few more) and B-2 can survive in IADS far harsher than B-1B has any right to be thinking about given its lack of cruise missile carriage.
Its resurrection was pretty much the dreaded "interim weapon system" idea rearing its ugly head: you bring in a new weapon system to "cover" the perceived gap between an older weapon (B-52 with AGM-86) and an even newer one to replace both the old and interim systems (ATB/B-2). Naturally, neither happened and the USAF ended up stuck with three measly bombers, but at least for the nuclear war mission you can scratch B-1B off because it's a complicated and expensive hangar queen, and B-2 partly exists. Which is more than most interim weapons managed. Imagine how terrible it would be if B-1B destroyed any chance of the USAF getting B-2.
The better option would have been to push for faster development of AGM-129 but I guess that was too far ahead. The B-1B decision was made in 1981 and ACM didn't really show up on the idea board until the following summer. Shame. It could have been the other way around and we might have another 100 or so B-52Hs and a conventional AGM-129 to show for it instead of B-1B. That would be just as flexible, better for nuclear strike mission, and a bit cheaper.
FWIW, there is no air defense system in the world that can stop BGM-109, let alone AGM-129, reliably; so I doubt AGM-86 was in any real threat from Soviet IADS for as long as it existed. It would be more correct to say "the USAF thought B-52H and AGM-86 would be bad in the future against the Soviets" which is a good thing to think at the time, in lieu of historical evidence to the contrary, but very silly to think after Beqaa Valley, Desert Storm, and the current Syrian War.
We know now that AGM-86 and B-52H were probably more than adequate for defeating any potential Soviet IADS except the fantastical ones in the manuscripts of technothriller authors. Suffice to say I simply don't put much stock in the then-much touted ability of B-1B to survive the Soviets air defense zones if a tiny cruise missile with a much smaller radar, thermal, and visual signature flying in a similar altitude somehow can't survive either. Or a plane flying similar speeds but because one goes very slightly supersonic (which increases almost all relevant signatures except radar) it can somehow survive despite the slower plane have longer ranged weapons and maneuvering decoys. Just doesn't sound right to me, but that's probably because it isn't right. Naturally US estimates of Soviet IADS beyond 1985 were wildly optimistic (for the Soviets) because all good defense planning paints you as weaker than your enemy so you can secure more funding for your pet projects. Take whatever they thought 1985 would look like and it would be closer to what 1990 actually was, which is the time that ACM enters service in large quantity and fully obsoletes the B-1B in nuclear strike roles.
So B-1B either dies a horrible strategic bomber mission loss to 1990s era Soviet IADS with MiG-31s and A-50s and gets relegated to bombing Central Asian villages, like in reality, or B-1B can never be built in the first place and you spend that cool big bucks on a shiny new cruise missile a few months later and keep some of the older bombers in service after the Cold War ends in 1990. I tend to err on the side of caution rather than rash action, so I'd probably start a Defense Welfare Fund with the $20 bn and use it as a trust fund/sovereign wealth fund, for DOD to spend on neat toys that no one wants to fund out of the annual budget that year. Or the government in general. The latter would be more beneficial to people in general, but the former would be preferred by the folks who frequent this forum, so take your pick. But I'm not President Reagan nor any of his advisors.
The USAF could probably run a wing of A-10s or F-16s for another 5 years instead of pushing harder for JSF around this time had the money saved from combat missions over Kosovo and Central Asia because that FY81 $20 bn allocated to B-1B was spent on keeping an extra 100 B-52Hs in service and developing a more robust and substantial inventory of AGM-129s to replace all the AGM-86s one-for-one. So in the best possible case B-1B has more or less cost the USAF a bunch of otherwise free money that could have been better spent somewhere else, and shortly after it was resurrected from the grave and the money spent pretty much all justification for its existence kinda fell out from under it, because the main concern (cruise missile survivability) was addressed by AGM-129 in totality. But AGM-129 post-dates B-1B by a few months, so it's kinda impossible to just reverse the $20 bn spent on B-1B for faster production of cruise missiles.
The fact that B-52H retained the nuclear strike mission for decades with AGM-129, and B-1B lost it less than 5 years after the USSR broke up, speaks volumes about B-1B's suitability to its alleged job in general. It was the weakest link in SAC's strategic strike capability, besides maybe the F-111s in Europe, and nothing could really change that because it was fundamental to the airplane's shift from a high speed, high altitude bomber to a low speed, low altitude one, which made sense at the time given the knowledge of the time, but given the understanding of the reality of the situation (and not that ephemeral perception of understanding at the time), it was a mistake. Evidently, one incorrigible enough that B-1B hasn't been a nuclear capable aircraft for most of its lifespan (since 1995).
Of course in practice the ACM had its own issues, like union strikes, production delays, and generally crummy management, so it's not really a panacea except in the airy fairy world of armchair theorizing. Given it came about right after the Cold War ended it wouldn't have added much at the end, besides give the B-52H a powerful long arm in nuclear combat. Perhaps you could throw $10 bn at Lockheed and $10 bn at General Dynamics and have them make 1000 missiles a piece or something starting in FY81 or '82. That would be really chad and cool, like when Century Series planners were cranking out simultaneous runs of comparable aircraft from different manufacturers to produce redundancy, but would probably be too big brained for the US at the time. Might even see service before 1989 and you dodge the dreaded "interim weapon" silliness.
TL;DR: B-1B was dopey for a host of reasons that made sense at the time, some of that being general zeitgeist, and some being a scant couple of months in lifespan, which make no sense less than a year after contract award. Within historical context, as much as any weapon system can be evaluated (TSR-2 comes to mind, as it's essentially the British B-1) using hindsight: it was a total mistake and in a perfect world would have never been built, at least not for the job it was built for (strategic attack).
In a completely different job, like that of a Pacific minelayer, it would have been alright probably, but there was a glut of B-52H for that.
So there's not much you can do. It was a mistake, for sure, but one you can live with, and we have, but it was still kinda dopey.
