I think you have a few things messed up.
For starters, Brom did art for the revised setting as well. He just didn't do all of it.
Najo said:
The brom era has a ruined world, found ruled over by tyrant sorcerer kings. The world is full of mystery and a lost past, the dragon is as much a myth as noone has seen the great beast, just heard stories or know of the offerings sent out into the desert by the citystates. The world is unforgiving but secrets lie in its waste and the ruins of a lost age speak of a more noble past. The races are all hint of this time, and show the scars of whatever ruined the world. Subtle things and differences set the mood of this setting, scavenged armor, weapons made from bone and obsidian, slave tribes, the thri-kreen as a player race, unqiue monsters (no typical vampires, werewolves, dragons etc). A world where water and metal are more precious than honor.
This is all in the Revised setting, too. The problem with the revised setting was they added something of a history. While I think the revised history of Athas is kind of lame, too, I like the idea behind it - Fans wanted history to their world, and the designers obliged. And they did it in such a way to make the game unique.
In any case, all of those things that you say are "brom era" are just as present in the revised setting.
Another aspect of Dark Sun that is overlooked is the political agendas. Tyrant sorcerer kings with secrets of an ancient and dark magic. The templars and their control over the social levels within the domains of their kings. The nobles and freemen, and their conflicts with the slaves and nomads of the wastes. The races with their differences. Elves vs Thrikreen. Rural halflings vs society. Scoiety vs Arcane Magic. Druids vs Defilers. Secret Societies, ancient secrets being protected or selfishly coveted. I can go on and on.
Here is where I really disagree with you. I think the revised setting had even MORE of this present. I mean, look at Tyr alone - it had the ziggurat problem in the original setting, but in the revised, it had so many conflicts between power groups that you could literally run a whole campaign without ever leaving the city. And every city-state got a similar, in-depth treatment.
There was a whole slew of information for running politically-based games; probably more than any other contemporary 2e setting.
I think a more accurate complaint you could make about Original vs. Revised would be the fact that in Revised, there was just a lot more detail (since each city-state in Revised got two or three pages, whereas in the original, each city got maybe two paragraphs, if memory serves).
When they revised Dark Sun, many of these story elements were ruined or turned into something silly. A planet ruled over by psionic halflings with organic cybernetics.
No argument there.
Killing the one and only dragon (the mythic symbol of the setting) by stabbing him in the nose with a magic sword by a 18th level gladiator.
I had no real problem with killing the dragon. What I did have a problem with was just how much TSR would tie novels into their game world. Thank god Eberron doesn't do anything similar. I wholly agree with you here, but I don't think it's a design fault; just a problem with TSR at the time. Novels sold money, and they had to make the novels Heroic. And that bled into the setting.
If you gave the novels a few more years, I'm pretty sure Athas would have turned into Toril. Only, you know, cool.
Bringing in bird and lizard men (taking somehthing from the Thri Kreen and making the races lose their hints of a previous age where their ancestors had honor and nobility).
Don't quite get what you're trying to say here. First off, the Aarakocra and Pterrans were both introducted BEFORE the Revised set; revised just made them character races (which I was alright with, although I think it was unnecessary to make good version races of a typically evil species, just so you could justify their presence as a PC race).
Second, where's this "honour and nobility" thing coming from? Elves had it hinted at in Original, true, but that was never really dropped. If it was dropped, it was due more to space constraints than out of any conscious design choice - hell, Elves in the novels always had this "previous honour" thing going for them, right till the end.
Windsufering halflings in a hidden last sea.
Techincally, the "windsurfing" halflings were found on the Jagged Cliffs, and they were a little cheesy (although I remember loving them when I was 15 or so... we played a Jagged Cliffs campaign that was a lot of fun). The Last Sea was an entirely different place, that had nothing to do with Halflings.
Artwork that lost the mood and feel of Broms work.
I actually like how the revised setting approached art. It seemed a lot more "tribal". And cooler.
Killing off half of the Sorcerer Kings (beings that defined the setting and were the most power creatures upon the world who lived for over a thousand years are slaughered one after another by dumb choices and low level heroes in the last book of the prism pentad).
Yeah, that kind of sucked. But, in the revised setting's defence, the removal of the SK's didn't really make things better (except, maybe, for Tyr). Think about it:
Raam - City absolutely devastated. Different factions tear it to pieces in gang warfare.
Balic - Three factions try to control the city; a limited democracy tries to get running, but flounders.
Draj - A false sorcerer king is put into power, controlled by a psionic elite.
Really, an argument could be made that the death of the SK's made the cities COOLER. Especially Draj - I didn't like it in the Original set.
You can look at the artwork on the covers of Slave Tribes, Valley of Dust and Fire and Dragon Kings and then look at books like the Will and the Way, Preservers and Defilers, Mind Lords of the Last Sea and the Revised Dark Sun setting and see exactly what I am talking about. If after that you still don't get it, well...not much hope your will
Meh. Truth be told, I didn't like too many of the covers in any Dark Sun product, with the exception of the Revised setting, and the Veiled Alliance. But you're right - there was an art shift. That's really a matter of personal taste.
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Anyways, my point in all this is that while the two sets presented the setting in a different way, the changes were a lot more subtle than "it made the setting stupid". The first three years I played Dark Sun, it was entirely in the Revised setting, and at no point did I ever say "man, this is dumb".
All that being said, I do agree with you - The original setting was better. Just not for the reasons you say.