So you think that makes it okay. Do you think a lesbian wants to date a man dressed like a woman? They'd be grossed out just as much as a straight man finding out their new girlfriend has the same plumbing as he does.
This is not about putting the transgendered down, it's about lumping a bunch of people together who have nothing in common and treating all the same.
Technically lesbians have nothing in common with gay men. Yes, they both have same gender attraction but neither group are related to each other in any way.