It seems like a common criticism that's leveled at D3 is that the skill and rune system will allow everyone to easily adopt cookie cutter builds. After all, you're just a few clicks away from the most optimal build, so why wouldn't you use it?
I can understand people not liking the skills system, it IS a pretty big departure from D2, but I think this specific complaint doesn't hold much water.
Diablo, as has been said many times, is more about viability than optimal builds. The problem with D2 was that too often the only viable builds were the optimal builds. There wasn't much room to get off the beaten path (in terms of builds) without ending up with a character vaguely resembling Forest Gimp sorry Gump. In D3, the fact that skills scale to weapon damage ameliorates this problem greatly, ensuring that many skills can be viable.
Some have said the problem with D2 was the balancing, not the skill system. This is only true to an extent. In any kind of skill tree, later abilities are usually more powerful than the starter abilities. While I guess this doesn't have to always be the case, I don't think it would feel right otherwise. So how in such a system could Blizz make the lower tier skills in the tree useful in endgame? Also, how do you make it worthwhile to spend more points in the one point wonders, like teleport?
Also, when do you think people will be more likely to try unique builds? When they have the freedom to do so, well, freely? Or when they have to level a character to 60 just to see if it'll work? (Respecs!! you might say. Respecs are just freespecs with a gold cost attached)
I've seen people try some pretty crazy builds in D2, but in most cases they didn't work. I think this desire is still present in the community, and from what I've seen so far the D3 skill system looks like it will satisfy that desire much better than D2 did.
(note: I'm not saying that you should love the skill system, or that any criticism is invalid. I was arguing against one specific complaint only.)