I am not averse to the concept of gaining buffs in response to CC provided it is only for particular types of CC (as opposed to all of them) and if the buff were related to the type of CC given without granting full immunity to it. For example, a particularly large and heavy character could deal physical damage in a radius (based on level and/or max health) in response to getting knocked airborne or rooted from the force of their mass hitting the ground, and perhaps having innate Tenacity (slow and stun resist) on account of already being so strong from having to heft his own weight around that you can't do much to slow him any further; or perhaps a particularly bloodthirsty champ could gain stacks when slowed, stunned, or otherwise subjected to movement-impairing disables that are consumed on the next AA or ability cast to increase its damage representing his growing rage and frustration at being held back from his intended target.
Just outright making a single character completely immune to all forms of CC and/or having buffs that counter all forms of CC would just negate most if all forms of counterplay short of "one-shot kill this thing while it still hasn't seen you" and be brokenly overpowered and unfun to play against. Especially considering how many champs' kits rely on CC effects; punishing too many champs for daring to do what they're supposed to do is hardly good game design.