The way i thought it was, and please advise i am new but from what I've gathered from people who stream etc on Twitch is the following:
DD's > CV's: CV's can hardly hit DD's due to there speed and maneuverability.
CA's > DD's: CA's are primary there to counter DD's from getting close to the CV's while also escorting the BB's from CV's Air attacks.
BB's > CA's: To knock out the escorts etc to give DD's a chance to get close to BB's and CV's.
CV's > BB's: Easiest Target to hit with Torps due to the nature of BB's Speed.
I don't get how the above is unbalanced or give one class a advantage or disadvantage at all. Considering if your team works together and completes the roles they are required to complete, and don't get me wrong lots of classes can kill the others but there primary roles where meant to be the above.