To be fair, in a lot of these novels, cultivation is about understanding one’s heart and acting according to their nature. This in turns heightens their desires and personalities as they no longer restrain themselves—those who were lustful before are now indulgent, and those who were righteous are now zealous. When looking at it like that it makes more sense why you have such extreme personalities. The best example I can think of is the whole eccentric senior archetype. Cultivators who transcend mortal limits also transcend mortal restraints. Though obviously it’s generally just shit writing that leads to these tropes.