Just look at fitness influencers, atheletes, male and female who have peak human bodies as examples, ppl like showing off their bodies when they are physically fit and look good.
I never got the whole oversexualized angle when it comed to most comic book appearences, they look very tame compared to rave or even gym outfits meant for mobility, do superheroes not need mobility?
God forbid they go on a run offscreen, and my logic was the powerless show off their bodies, so why wouldnt ppl in their costumes, not necesarily that the powers give them perfect bodies, their lifestyles give them perfect bodies.