Tera: The problem lies with making different classes actually feel different. Take WoW and the warrior and rogue, both melee classes. One has intercept/charge, the other has cheapshot and kidney shot. One has pummel, the other kick. One has a -50% healing debuff that does high damage but has a cooldown. The other has a passive -50% healing debuff that does low damage, but can also be removed. One can reflect spells with a shield. The other can become immune( or 90%) to spells for 6 seconds.
One stuns, one gives increase move speed and damage. While they have the same design for mobility, control, and so on. they are different in how they go about achieving these designs. The problem lies with this flavor and how it ties into other classes(Tera Gold). Maybe the classes they play with cover their weaknesses or strengths. Maybe their flavor combined with another classes flavor makes both of them together some amazingly awesome powerhouse setup that can only be brought down by the hand of God. In the end it sounds nice to balance every class around 1v1, but it's not realistic. The moment you change that 25yard stun to a 25 yard root, you have changed balance(Tera online Gold).