Except there's little to no treasure, and magic which you can use without issue everywhere else in the multiverse actually harms all life around you. I just don't think why a party from somewhere would like to go to Athas. A DM might want to do a "Your ship crash lands in this incredibly hostile planet!" scenario, but I think even that ruins Athas's own lore just to make a quick one-shot adventure. The larger themes of a post-apocalyptic setting where the only hope is to fight the oppressors is just gone when you have the better option of getting the eff out of there with a ship.