Well, in the lore of the game, arcane corruption is based on your subjective morality, but since it would be at least extremely complicated to adjust that to the player’s subjective morality, it needs to be an abstraction of the squire character you’re playing and their morality. That character isn’t entirely “you,” it’s you in a certain context, with a certain background and a certain society, so the morality is that character’s society plus what you as a player interpret to be the reasons behind corruption (again, it’s not clear to any of the characters and shouldn’t be totally clear to the player). Also keep in mind we can’t choose our morality, it’s shaped by our background and our society, so even if I technically could give the player the choice of their morals, that wouldn’t exactly be realistic.
Also, in regards to the physical deformities thing, I tried not to make it scarring or any real world attribute because A) I didn’t want to associate morality with body shaming and B) it’s actually up to you whether the physical manifestation is a negative thing or not. Arcane corruption can actually be one of the most useful stats in the final battle (if you even want to win the final battle). So that’s where it then becomes a player subjective choice about morality and their reaction to the game’s morality.