What judgement? That slavery is one of the most horrific things in history? I don't think that's too much of a stretch. That slavery is equivalent to things like genocide in its level of horror? Again, I don't think that's a terribly unfair judgement.
But, ok, fair enough. How would you present it? How would you present slavery in Dark Sun in such a way that it's handled with sensitivity and gravity in our heroic fantasy game? What art would you use? Please, specifically detail how you would describe slavery and it's use in the game.
Everyone wants to wave this magic wand and say, "oh, it's not really problematic". It's easy. We'll just magically get WotC to thread that needle with ease and grace and we'll get that Dark Sun setting we all want.
So, let's see it. Let's see someone here step up to the plate and give a decent example of how you present slavery in D&D that would be acceptable to the publisher.
I'll wait.