To me, the proper re-introduction of CC will make instances not just boring AoE zergfests, and will be one of the biggest indicators for whether or not a player has any notable skill or worth. Don't know how to open your spellbook and find a short-cast (sometimes instant) spell that temporarily crowd-controls a target? Get the hell off my internet.
Avoiding breaking CC is harder than using it, as Sass said, but is still pretty damned simple. Here are a few pro tips:
* Don't hit something that's CC'd
* Don't use big bastard AoE attacks near something that's CC'd
* Don't use consecrate on top of CC'd mobs
* Don't break the CC.
Simple, huh?
It might make PuG'ing a little harder. To be honest, I couldn't care less. Hopefully it'll drive the retards back under their rocks, or force them to learn how to not be so hopelessly shite at the game.
For all the "simplification and homogenization" crying I see about Cataclysm, I also see more skill going back in; healing won't be so simple and spammy, CC will make dungeons/raids a bit more than tunnelvisioning DPS-happy zergfests, and hopefully the most faceroll DPS specs will require a little more attention to play and not resort to FCFS rotations (don't get me wrong, I enjoy Ret now, but I'd like something a little more skilled than it currently is, since the height of skill for me at the moment in terms of just the DPS aspect of my spec is dealing properly with the mana hemorrhagingly awesome 2T10 set bonus)