One thing I noticed with the sample Dark Sun PCs is that they did not, as I thought they might do, use a larger point buy value for them. Combine that with the reduced variation in racial mods (bonuses only, no penalties), the elimination of class based attack bonuses, and the lack of support in the Character Builder for anything other than a 22 point buy for a non-houseruled game, and it looks like WotC is going for a consistent and narrower range of ability scores across the board -- the game is that much more sensitive to ability score variations from earlier editions.