I'm no expert, but the feeling I get around various Dark Sun communities is that 4e Dark Sun was, overall, well received and if it's barely talked about now that has a lot more to do with the 4e part than the Dark Sun part.
I played in a 4e Dark Sun game.
I'm not a huge expert on Dark Sun lore, but my experience was generally fine. A little disappointed by the exploration/survival aspect being so small in scope, and a little disappointed by the defiler mechanic being not super enticing, mostly.
With the survival aspect, I'd expect the wilderness on Athas to be able to kill PC's with the weather well into 5e's Tier 3. I'd expect even well-worn trade roads to challenge Tier 1 characters, and most wilderness areas to be a reasonable risk for Tier 2, with maybe the more extreme zones in Tier 3. 4e Dark Sun's weather wasn't a major issue for us ever. Just an aesthetic.
With the defiler mechanic, I'd expect a rule where arcane magic kills things by default and you have to do something EXTRA (make some effort) to stop doing that. The 4e rules made defiling an opt-in thing rather than an opt-out thing, which hurt the vibe because then arcane magic was just normal for the party and no one really had an issue with it. Which isn't what I'd expect in this setting, where to be an arcanist is to be complicit unless you know some secret and do hard things.
But the character options were cromulent and the setting still had that "fighting against the apocalypse" kind of vibe in the antagonists that the DM chose, and all of that went a long way to having a good time with the setting, even with a few structural problems in the design. It was cool to play with more psionic PC's, and I really enjoyed my two characters (a thri-kreen monk/ranger, loyal to one of the Sorcerer Kings, who mechanically was just there to get as many attacks as possible in a turn; and a water genasi swarm druid who I flavored to be a human whose powers were about summoning water but who could never keep the water around, since it was just a magical creation, someone who was haunted by their failure to bring back water and who mourned the world each time she used her powers).
A 5e Dark Sun in the vein of the FR setting books could be a nice thing. I especially enjoy the adventure options in the 5e FR books, and I think a 5e Dark Sun could really show the setting off with a few of those. 5e is also kind of overdue for some robust psionic options, and it would be cool to have some deadly environments and to get another take on what defiling could be like as a setting element that costs you something to overcome.