I think it's because everyone is so focused on how hot he is because he's a "normal" American musician. If they look like the guys that girls fall for in highschool, then they're more accepted. Bill was the kind of emo kid in school, and nobody really likes those, so now that he's basically an overgrown emo kid that looks like a girl, everyone thinks he's a freak, which sucks because he is so sweet to everyone. People are afraid of what they don't understand, and as soon as someone tells someone that Bill's actually a boy, they freak because they think there's something wrong with him just because he has a great sense of style. It's called metrosexual. Get the fuck over it, rest of the world.
Oh, I know. I just...I guess it's because I'm so accepting, but I don't see any reason why anyone should hate Bill. He doesn't even DO anything to them for Christ's sakes. He's the sweetest guy on Earth and he's never done anything that would classify him as a jerk like other musicians have. :L