I don't think humans deliberately set out to make the world very hot. If you don't intend to do something how can you do it intentionally? Equally I don't think it's possible to make Mars have more gravity without adding more mass, which would be a prerequisite for humans to live there.
If Venus has a breathable atmosphere you can live on it just fine. It's basically Earth 2 in all meaningful metrics. If Mars has a breathable atmosphere you can't live on it. It's too small and the gravity too weak. Humans didn't evolve in 0.3g, they evolved in 1g. Venus has very slightly less than 1g, but it's within the average of Earth's gravity if you measured it.
The further you get from conditions where humans evolved, the harder it becomes to live. So why make things more difficult? You wouldn't. No one does this. The only reason people like Mars IRL is because it's easier to imagine living on a dry, cold, dead rock than it is to imagine living in a hot, muggy, high atmospheric pressure Earth.
You also complain about me thinking that time preference is a barrier to space colonization, which is arguable (I think it's born out by evidence, but that's an open question as well given we aren't great at making rockets yet still), yet you suggest that a literal subspecies or likely new species of Homo adapted for living on Mars would be a preferable alternative to humans that can think about resources in a longer time horizon? Lol. The difference between a species that doesn't care (or is genuinely happy about) that it's living in a Space Amish subsistence farming economy with spaceships, and a species that is adapted to 0.3g, would be probably be wildly different in anatomy alone much less thinking. If you care about human life then only Venus makes sense.
The truth of the matter is that Venus is the easier of the two to colonize over multiple generations, by virtue of being closest to Earth in conditions, especially conditions that are beyond plausible control. It's relatively easy to adjust a comet's trajectory to impact an object (we do this all the time on smaller scales) compared to restarting a dead geologic fossil or increasing a planet's mass triply. It's one thing to suggest that people, in a million years (they are no longer people at that point, they're probably some other animal), might make a planet bigger. Maybe.
But then you'd probably just make a planet wholesale from a star or something. So why bother with Mars, again? It has no advantages in the scenario. Its only advantage now is that it's much easier to get there and get to the surface because it isn't covered in a giant atmosphere.
Venus for sure. Mars less so, as there's nothing there worth looking at now, much less if we could easily access Venus's surface.
Mars's interest would be for biologists in the same sense that Antarctica is interesting for climatologists. This won't change with a breathable atmosphere, it will just be more well known and accepted in general, since no one actually talks about the issue of embryo development in microgravity or reduced gravity.
Humans (and most terrestrial life besides microscopic forms) probably can't survive without natural or artificial selection adaptations in conditions too wildly different from Earth norms in terms of oxygen-nitrogen balance, temperature ranges, and gravities. This is somewhat obvious, I think. Spending time in space is bad for you, after all, and you're still under the effects of the Earth's gravity in orbit.
Once you build all the radiation protection, the greenhouses, the powerplants, etc. you still have to face the issue of reduced gravity that no practical engineering can fix unless you want to install a multiple hundred meter long cylinder centrifuge and use that as a basis for a colony. But then why not build that rotating habitat in space where it's much easier to maintain and construct new equipment and replacement parts for?
Mars's biggest issues are because it's a planetary pebble on the extreme end of the habitable band of planets. This isn't solved by making it breathable, it just becomes more evident, I guess.
Conversely the only barrier to not living on Venus is because it's covered in a thick smog of sulfuric acid. You remove that you've just made a second Earth that's slightly hotter, but since it's breathable and livable it probably can't be that much warmer.
