Remathilis
Legend
[MENTION=7635]Monks in DL is not unbalancing things. No Dragon riding Knight of Takisis will be impressed by a Monk.
Monks in DS unbalance everything, the survival vibe, the inferior weapon / armor System, all of that does not hamper the Monk the slightest but almost every other class / build (Same goes for barbarian in a way)
The "why not" is any use of arcane magic causes environmental damage. This is central to the setting, so full caster bards should be defilers.
Personally, I would rather throw out caster bards and introduce a non-caster bard as a rogue subclass.
See, this proves my point. Dark Sun, in order to be done justice, has to ban or re-write most of the PHB. Its elves are different, its halflings are different. It doesn't have gnomes, it doesn't have tieflings. You can't be a monk, a paladin, a (spellcasting) bard, or a barbarian (Seriously, the CLASS modeled after Conan is broken in the WORLD modeled after Conan! SMDH). You have to re-write druids, clerics, wizards, rangers, and warlocks, and ban huge swaths of subclasses. You have to ban spells, create a whole new equipment chapter, add harsher survival rules, weapon breakage, and defiling. And we haven't even touched psionics yet.
Besides the basic math, how is this even still a D&D setting? It has as much in common with D&D as Star Wars d20 did. Its almost on par with The One Ring 5e.
My point is that doing Dark Sun requires one of two choices: it needs to be its own game (separate but compatible with D&D 5e) where it can get its own player, GM and monster guides that fit its themes perfectly, or it needs to swallow its pride and accept that paladins, monks, warlocks, dragonborn, and such have a place in it. The latter has prescient; 3.5's Dragon conversion and 4e's conversions both found ways to incorporate these elements into DS. But the absolute worst of both worlds is a book that tries to kludge a system out of the PHB with a long list of "not alloweds" and "use X to represent Y" style stuff.
Anyway, I derailed this thread too long. Yay Mystara, a setting that requires 1/10th the amount of work to convert to 5e.