As a DD main, I will tell you my points of why CV's BELONG in the game. I started playing CV's to learn how to play against them as a DD main. But just a couple quick reasons.
A good counter to a good DD main
Spotting that is often needed because current DD meta is not the easiest climate to play
A good counter to some of the better bow tanking ships
A good support unit for the other flank (non-lemming flank), when a team lemmings, and/or so a flank that is falling apart can slow an enemy's push in order for your fleeing teammates to take better positions.
Mahalo,
-Hapa