I could be off the mark here, but you do realize people want to be given suggestions as to why monsters are evil and monstrous?
They're not misunderstood, they're not mistreated, they don't do it for logical or forgivable reasons, they're not redeemable; they're simply ugly, horrible, smelly and in need of a good killin'
Whose a better villain, Lex Luthor, The Joker, or Hillbilly Bob the big ugly smelly guy?
I get that there should be some enemies like this, but... seriously, I think most under CR 8 humanoid monsters are disgusting or ugly in some manner. Trolls, orcs, gnolls, goblins, ogres, hill giants (which are frankly identical to ogres), ettins, cyclops, Fomorians, Bugbears, grimlocks, troglodytes, jackalwere, wererat, Meazel, ect ect ect
Honestly, take the Ogre, The Cyclops, The Ettin, the Hill Giant and the Troll. All of them are big and strong. All of them are ugly and stinky. The Troll is the most interesting one because it regenerates, lives in the most interesting environment (not a cave like all the others) and has variants. The Hill Giant and Ogre are identical looking except one is bigger and stronger. Cyclops are exactly like ogres only with one eye. Ettins are exactly like Ogres except two-heads. It just feels.... like if they tried to introduce another large sized, strong creature that is stupid, ugly and smelly, what would be the point, we've farmed that ground to death. There is nothing left here. Move on.