This would, as previously mentionesd, only cause one to do way more leveling. Also It's a ton of work for the game designers to balance it all in a way that there's actually a choice. Someone has to do that too, Ideally without having to change the complete mechanics of that class. CC skills are not a need to have thing. Maybe when you're raiding, but I think, especially from people wanting to do high-level content, it can be expected to go a little out of your way to unlock them.