The Tavern

Demonspawn body mutations are cool in a thematic way, but often a letdown in game (your +20 boots of the violet are not usable anymore! Have fun kicking people from range!).
Monstrous demonspawn is problematic, because you don't really get what you signed for.

My proposal is that of having a Monsterkin species, which is in effect a monstrous demonspawn, starting with level 1 of all body mutations and powering up during the game until you reach full size, while removing all aux attacks mutations from demonspawns and monstrous demonspawn.

This would allow for a good UC user who is living and medium sized, with decent hybridization options.

Why would it be better than monstrous demonspawn? Because you would play it if you want to play it.

demonspawn have a chance to get randomly screwed over halfway into their run. to the dev mind, this is "unique" (tavern meme) and is therefore also "interesting" (another tavern meme). most importantly of all, it causes players to complain.

combine all these factors and it becomes apparent: monstrous DS will never get removed.

You get to know if you are monstrous by d:2 or whatever. Not like you just spent 8 hours playing to have your gameplan ruined (unless you are super-slow)