The same reason women are attracted to gay men. Anyone who doesn't believe that this is a thing...One, stop being a dumbass, and two, look at any teenage fandom featuring more than one attractive male character. You will find a ton of evidence.
Even as a pansexual I have to admit...lesbians are hot. Might have to do with the fact that almost all men in pr0n are ugly or masculine. I prefer femininity over masculinity, except in women. Basically, I prefer feminine men, and either extreme and everything in between for women. (Yeah, I know. It's complicated.) But anyway, yeah, lesbians are hot.
We also need to find a non-offensive male term for a gay man, like lesbian for women. Why should gay women get a gender specific, non-offensive word for themselves?