(For the record, I of course fully agree here.)
I've asked this before but have not gotten a response: Why is slavery so fundamental for Dark Sun?
It has water and metal being worth more than gold. It has environment-destroying magic. It has psionics everywhere, to the point where even simple animals have psychic powers. It has a wasted, post-apocalypse environment. It has almost none of the traditional D&D monsters and tons of very weird ones. It has some strange new PC races and unusual twists on existing races. It really requires resource management to play properly. It has no gods, putting elemental forces in their place. It has a very different culture than any other D&D setting.
One would think that any of these other aspects would be far more important to Dark Sun.