In an interview with YouTuber 'Bob the Worldbuilder', WotC's Kyle Brink explained why the classic Dark Sun setting has not yet seen light of day in the D&D 5E era.
I’ll be frank here, the Dark Sun setting is problematic in a lot of ways. And that’s the main reason we haven’t come back to it. We know it’s got a huge fan following and we have standards today that make it extraordinarily hard to be true to the source material and also meet our ethical and inclusion standards... We know there’s love out there for it and god we would love to make those people happy, and also we gotta be responsible.
You can listen to the clip here.