It's a great idea, but it will force Majalis to rewrite the dialogs and depending on the code they've written, it might be difficult. If they foresaw it, then it's quite easy to automatically change phrases in text, but otherwise it would take a lot of time. It's kinda the same problem as with my suggestion : creating a temporary transformation (just an excuse to put the game on the tfgamessite) is okay, but keeping it permanent? That would mean (1) either changing ALL encounters or (2) creating a temporary sub-zone with several predefined encounters and forcing player to stay there until the transformation is reversed.
Now, let's return to your topic :)
However, if there are indeed a lot of people that would also like to play as a herm character, adding such character options might be worth it. Though I doubt that it will be a real herm (with a vagina and a penis) as in many encounters (Centaur, Vagabond...) it is the point that the Main Character doesn't have a pussy. Having a choice in the size of breasts ( flat(femboy), A cup, B, C... ) is totally possible however. If you think that is enough for you, I think Majalis will no doubt implement it sooner or later.
Hah, the changes in breast size can totally count for tfgamessite : by adding them (and allowing/forcing to change them with some encounters) Majalis can kill two birds with one stone :D