I was thinking of the cc role in a party, and with that, i start to think about the mob stats. We only can se her life as percentage, but i believe they've different stats for physical, elemental, divine and nature defense, as for attack stats. I suggest for the new mechanic of CC stats to be implemented to bosses instead of they being immunity, of course some bosses skills will need to be changed to not be cancelled (also one boss or other could has an cc immunity buff). I think it could bring a new bunch of mechanics for dungeons, raids as the game world.
Imagine a boss having a massive willpower, that make cc skills only last for a irrelevant period of time, other that some times enter in a cc immune mode or a boss with a huge sustainability that make cc him worthless.