There's a lot you can do with additional displacement, though.
I'm currently looking into a rather crack-pot design... a 20,000-ton Carrier with 7,000 tons of Hangar space, whose "strike group" consists of a single 7,000-ton ship, stuffed inside the Hangar.
Why? Because Box Launchers can only be reloaded in a Hangar (or on the ground)... so this arrangement allows me to use... and reload, and re-use... a 7,000-ton, 85x Box Launcher equipped warship, in a general fleet action.
Can you say "massive salvo"? I knew you could...