You still need to be physically there with an asset covering airspace with regards to air combat. The ground threats have also changed and improved since the 90s and are likewise more effective. Any modern fight with a peer adversary is going to last a week or two and I would prefer to have more than just enough that is needed in a simulation."A handful of F-35s can accomplish the same mission objectives, or desired effects, as it might take 12, 15, 20, 25 or more other aircraft."
This argument may cut both ways. Sure keeping on buying the F-35 is the better alternative, but if its so effective, why need a 1-1 replacement with legacy fleet.
Sure a f22 can defeat 6 migs but it can replicate itself to be everywhere at once. And so it is with the F-35.