One of the previous threads in this section, made me think of another scenario:
What if Venus or Mars were inhabitable for humans?

I mean REALLY inhabitable, with liquid surface water, plant life (potentially usable for food and medicine),
a breathable atmosphere (or, let's say, at least breathable with a filter).

We would only have discovered that for sure in the last century, of course.

But what would the impact be?
For a start, nobody would question a manned mission, I guess