Personally, I think the biggest problem is actually the general lack of penalty for low stats. The main reason previous systems designed to remove randomness from character creation had trouble (and have been tweaked to the point of starting with 5 10s and an 8, then adding more) is because the benefit for having 18 in a primary class stat was far too large to be overcome by the penalty for low scores in non-class abilities. I think it would have been nice if 4e had tried to overcome this in some way (for example, it could add together 2 stats for your defenses, instead of taking the higher one, but give a lower base value - so 8 + Int mod + Dex mod or whatever). As is, we have PCs with all high stats, so an 8 int is as dumb as a PC gets. That's actually fine, in its own way, but it contributes to the disconnect from the 3d6 roll that makes this system seem outdated. Another possibility that would have been nice is if they had made a table of potential score distributions, where the more wildly skewed distributions had fewer total points, and the broader distributions more total points. I know the current system does this, but I mean do it such that I can play a character with 4 Int if I want, I just don't get some obscene bonus in return.
Maybe a house rule is enough...