It's nice in theory to say buff X power set but not Y when Y's only advantage of X is the buff you want to give X. You cannot take away the advantage Y has without giving something in return.
Example: You cannot give another set the damage of Fire bringing it up to par with Fire, without reimbursing Fire for the lost ground it is going to have. The under performing sets have side effects to their powers which are supposed to be the trade off for the lack of damage (slows, end drain, etc).
You cannot buff one without buffing them all. You can call out for a damage buff to them yes, but you have to buff them all the keep the secondary effects not more of an advantage.
I only took fire because it was pure damage when the game came out, I only play it now because it is pure damage. You cannot take away it's bonus damage over other sets without some sort of reimbursement, like reduction of all of its power recharges to compensate, making it a faster set than others.
