I think cool downs in some game are fine, and Im ok with that. With that said however, if its a Dungeons and Dragons game , excluding ( Neverwinter online and DDO ) that should always keep it faithful to the core rules, Like Bg 1 & 2 Neverwinter nights 1 & 2.
Those were faithful as far as I could tell. So if its natural abilities, spells per days what ever it is , keep it true to the PH , DM guide and I think will be ok.
-Doom
Except in the case of a machine gun overheating, i can't find a single case where CDs makes any sense.
PS : DDO, SCL and Neverwinter mmo aren't good games exactly because they felt more like a wow clone than a D&D adaptation...