I don't see personally why it would be any more difficult, although I'm not an animator myself. (I guess sometimes the guys have less detail or are partially off-screen, whereas if you have two women you'd want them to be both detailed and in-view, so there's that I guess.)I see what your saying i guess the bigger issue is trying to animate some of those things correctly isnt easy imo
I think it's more likely that the demand just isn't there.