For FTMs I think I get it. It's a form of validation. Like "Oh I'm really a guy because I'm gay and gay guys can be feminine!" Like it's easier to pass and also less gross than a gigahon claiming to be a butch lesbian.
But why do straight women love them so much? Why does Yaoi sell so well with them?
Are there certain aspects of gay relationships they prefer? Like I've heard some theories that they get off on the couple harming/abusing eachother.