If Dark Sun is really about embodying a heroic character who doesn't do the Clearly Evil Villain Stuff, then we don't need player-facing rules for defiling. PC's are exceptional, every PC spellcaster is a preserver, because defiling is Clearly Evil Villain Stuff and PCs are meant to be heroes. Defiling isn't something heroes do -- it's Clearly Evil Villain Stuff. NPC's can defile, and it's the PC's job to stop them.
If Dark Sun is in part about fighting against the lure of how easy and effective the Clearly Evil Villain Stuff is, then there's room for defiling PC's, at least as a kind of fail state for those who succumb to the lure of the Clearly Evil Villain Stuff. That's an appealing conflict, but harder to make a game for if your audience is millions of people, including a lot of kids. Not impossible, but challenging, because the possibility of BEING an evil villain (even as a fail state) means including the possibility of your magical elf fantasy game characters doing nasty things, which isn't something every table is able to handle.