Joel simply exemplified sexuality in general, as he takes credit for doing so on many docs in the SE DVDs. It wasn't so much a homosexual undertone, just a sexual tone. The seductiveness of Poison Ivy and the alluring qualities of Chase Meridian. Through this, Joel decided to equally demonstrate a sexual tone in the men as well- via their Olympian sculpted suits. I imagine most straight directors would have been too afraid to equally show men in the same light of sensuousness as women so he therefore gets branded as making Batman gay!
Schumacher says on the Shadow of the Bat documentary that he liked how the men and women are so anatomically rendered in the comic books and he just wanted to put this on screen. I personally think it was a fine idea to display the affinity and sexual tone of the characters just as you would find in any Jim Lee comic book, it simply took a gay director to equally show the men and the women in an equal tone. With that said, there are parts where Joel went too far, the butt shots of Batman, Robin, & Batgirl, as well as cod-shots were unnecessary.