Crowd Control Value
Champions that have more, or more effective CC, are not giving up anything to have it--they don't do less damage or suffer from lack of mobility. For example, Riven has TWO hard CCs and she is not under powered.
Champions that have more or better CC are just...well, they are better off all things being equal. I don't see any trade off where having one thing means you have less of something else.
All I see is champions that have better kits than others, because Riot doesn't understand that abilities that are both offensive and defensive are so much more powerful in the game than abilities that just do damage.