Basically CC will make a lot of things easier, but it may also make them slower. With CC you can do content you may not otherwise be able to do, but after 3.0 you can do heroics without CC with pretty crappy gear (heroic MgT 3rd boss being the possible exception), so it's unlikely you'll need it. WotLK is another matter. Heroic content isn't very explored as things are now. Blue posts have suggested more movement related fights, compared to now, but it's pretty much all speculation. We'll just have to wait and see, but as far as BC is concerned, you'll probably be fine without CC :-)