Why can’t superhero movies be sexy anymore?

"A large portion of the movie serves the purpose of showcasing how hot Uma Thurman is in green latex."

AND THE FILM ENDED UP IN THE TURD HALL OF FAME🙄

Well, it's for a different "demographic", but...300?

This movie was as sexy as the change rooms after a senior citizens water aerobics lesson.

Besides, you don't think Gal Gaddot was a bit sexy as Wonder Woman and had a romantic subplot with Chris Pine? Or perhaps Henry Cavill as Supes and his romance with Amy Adams?

I think you're worrying yourself unnecessarily.

I think OP is referring to the constant sexual innuedo that was is this movie than proper romance or love. The innuendo in this movie feels more like it would belong in an Erotic relationship rather than a properly loving one. Catwoman had Halle Berry showing off in a very revealing suit that was a bit complained about, but otherwise was not an issue. But when you practically make the two superheros nude (seriously, examine the batsuits very closely and it will clearly look like they are naked) and use sexual dialouge more suited for an adult film, then people will bash it.

I'd argue a larger portion is dedicated to ass shots of Batman or Robin, but I see what you're driving at. Not sure what exactly happened but it's rare for comic book films to have sex appeal these days, whether it be innuendo or costume design. I think Sin City 2 was the last one trying to milk that element of its source material and that was in 2014. Bugger me, strike that. I forgot all the camera ogling at Harley Quinn in Suicide Squad.
Perhaps they just caved to pressure from the usual suspects. You know, the fire-and-brimestone televangelists and their legions of puritanical soccer moms crying 'think of the children' along with backup from ironically enough their archrivals, the feminist bloggers griping about sexism whilst bearing their cleavage on Youtube.