Lets take chess as an example. What if suddenly the King could move around like the queen however only the Black side could have this power. But the white side could not. Would you say then that you can not balance chess to make all players equal skill?
True skill is when each side has the same powers and equipement available and yet one side still prevails over the other side with out being given a handicap. A chess player knows this fact.
You have come up against carriers that move in pvp with effieciency of a queen in a chessgame? You analogy makes no sense, as the two factions in STO are not designed along the same parameters and do not fulfill the same role.
As far as I know nobody has handicapped the feds or the Klingons in pvp and the skill involved in playing pvp is in the knowing how to load-out a vessel for survivibality, damage and possible support healing based on your desired role in combat and then how to use said vessel well enough to not be a detriment to yourself or others. Your analogy doesn't fit.
The bottom line is the Carrier was given to the klings to appease them for their lack of content. Nothing more. It was a bone thrown their way.
The lets us continue to enjoy our bone while the feds get the steak and leave it be. Or as I heard alot when the KDF was up in arms over being ignored, " Learn to enjoy what you have. "