First, there is the concept of threat. Each method of crowd control angers a monster to varying degrees. Add to this the other abilities a crowd controller might have used previous to controlling the mob -- a hunter plinking away at the mob a few times to get its attention, for example -- and the CC'ers threat is pretty darn high. The monster, once they are free, will have eyes (and claws) only for the group member that kept them tied down in the first place. It makes sense, honestly. I know if someone shackled me to the ground for a minute or so I would be pissed. Because of all this build up of threat, Karthis says that just breaking the crowd control will not be enough to pull threat off the CC'er, and they will end up clobbered on for a few seconds before you get their attention. Instead he recommends that you use Growl, or a similar taunt ability, to move yourself up the aggro list to be equal to the person that performed the CC on the target. Being that he is, after all, a bear tank, he then says use a Mangle or Maul and you're good to go.
As a mage I see this process from the other side. While a good tank goes a long way toward keeping us alive, it's important that the CC'er does his/her part as well. When you perform some method of crowd control, it is then your job to do what you can to drop threat. For mages this means Invisibility, for hunters Feign Death, priests Fade. As much as I love mage tanking in low stress situations, in the end the death of a squishy means the group has to work a lot harder to bring down the mob. Crowd control is all about control, and if the crowd begins to control you, then something needs to change.