Hear me out:
Survival mode.
Add a hunger mechanic that tracks what you eat. Obviously filling the bar would grant the Well Fed buff, but low bars would result in a massive debuff that would result in an incredible increase in difficulty. Obviously one could try and snack on rations and tavern food the whole time, but transformative items would also fill the bar, like cackle berries and knotted peppers. Kind of ends up in a chimera-ish, scratches an unwilling TF itch, and gives it a mildly more natural feel.
Maybe even take it further. A sleep function that debuffs over going too long without sleep and grants sleep deprived players greater chances of strange (read: sexy) dreams. Stronger nighttime encounters. Etc.
Otherwise I’m just waiting to bang more furries. Come to think of it, more exotic creatures, too— When do I get to bang a dragon? Or a beholder?