I think the "class skill" problem is not that there are class skills, but that (a) the Fighter does not get Spot and Listen as class skills, and (b) cross-class skills cost twice as much, not simply that they're limited to half as many ranks as class skills.
On a, I totally agree. I mean, what the f---, even Commoners have those skills.
On b, I think it's a combination of the two. If cross-class skills were limited to half the ranks but still cost 1/1, you'd have less trouble with the PHB2 retraining rules and dipping in cross-class skills would be more common, but a lot of skills that call for opposed rolls would still be pretty worthless to take. If cross-class skills were not limited, but still kept their cost, you'd see people more freely cherry-picking one if it was important, but only one, since it'd be all they could afford.