@The:
If you oppenet selects the Cv as the OOL you always retreat and cost them the fighters it turns out better for you as you can then attack again especially if the Cv has one or two turns to take before it reaches a port
As the attacker yes, it’s great when your opponent takes the CV as a hit (and especially if they have nowhere to land the fighters).
As the defender, you don’t get the opportunity to retreat so if the attacker takes the CV as a hit, they still have more offense than they would if they lost a fighter (even if they end up losing all their fighters in the end, they have a greater chance of winning).
I guess it all depends on which side you’re on and how badly you want/need to win that naval battle.