Restoring the defiling and preserving dichotomy to the Dark Sun setting

I’m not sure I agree with that. Mechanically, they may need some work, but fluff wise they are very rare and I don’t see them undermining anything. Wizards caused the setting to exist as it is through misuse of life forces. The Cerulean Storm is powered by Tithian and Rajaat’s life forces, the Grey by the life force of the dead who haven’t had it completely absorbed, the Black is the shadow of life and it’s possibilities in the future, siphoning power from the source of all life, the sun itself and maybe even from the Shadow Wizard himself (could be the cause of the coldness and shadow taint).