Is it dumb of people to judge the game just based on the cover? Yes it is.
Dumb people exist. Their money is as good as anyone else's. If they really would buy the game if the cover was changed in that really small way, then change the cover and laugh to the bank with their money in your hand.
If Larian changes it, suddenly they'll seem more responsive and enlightened - that's good publicity.
2. I have no idea what "Part of Larian's humor if you ask me" is referring to or what it means. Do you mean the Dragon Commander feminist with the dominatrix catsuit (with boob window!)?
3. It looks good to you. To other people, it looks stupid because the guy is in sensible monster-fighting armor and the girl's guts are protected only by bare skin. It may not be overly sexual, but it's impractical for no purpose.
As for the asethetic, I do like that aesthetic, and I am fully confident that the artist who made that great cover can manage to add clothing without ruining the entire thing.