Johnny does great damage, what the fuck are you talking about? Raising his damage output is not going to make him a better character because that's not his problem.
Like seriously I'm sorry but have you ever watched a Johnny? If Johnny has the correct resources (the fact that he needs resources so badly is one of his problems...not his damage) and pressured you AT ALL (you blocked a HS button) and then got hit, you're eating a big chunk of your life.
Johnny doesn't get shit all without at least 25% and level 2. His mixup is pretty sorry (his 5D is horrible, TK ensenga needs 50% to be safe and net you big damage) without meter and his pressure is significantly weaker without coins (mist cancel is not strong at level 1). The damage he gets when he finally has his resources and hits you is far and away from being a problem at all, it's the fact that he has to rely so heavily on meter and coins, both of which are limited.