Rather than go for a quick fix or simple nerf, I would rather that the combat mechanics and ship designer receive a decent overhaul to address not only carriers, but other issues with the game, such as target overkill, the economic bias to larger hulls, and various exploits like sensor barges, dreadnoughts that can move a 100 hexes per turn, etc.
One of the things I would like to see introduced is the concept of a TURRET MODULE. So you have to equip ships with turrets: either a small number of big turrets, or many small turrets, and possibly massive turrets costing so much mass they couldn't fit on the smaller hulls. Then you could select a weapon type for each turret, with the range, damage, accuracy, re-fire rate etc linked to the type of turret. This would also address the overkill problem where a ship can only fire at 1 target at a time. Now each turret can select a target depending on it's size/profile/ship role.
This way you can equip larger ships with tiny turrets specialised for AA duty. This gives the designer the power to design either a Yamato or an Aegis type ship, and creates the concept of "capital missiles", "flak cannons", etc all in one package.
BRANCHING TECH TREES FOR HULLS
Also, I would have liked to see more hull types, differentiated not just by size, but by specialisation ....
- spinal hulls, for support modules, bonus for sensors, hangar bays, troop transports, range, and other support modules etc, but penalty to armor and turrets.
- shell hulls, which have great armor, bonus to armor and turrets, but penalises support modules.
So you would two tech trees, one for support hulls and one for armored hulls. The trees could then have techs for upgrading of fighters, different turret types, etc.
While ideally you should build fighters into a pool that the carrier has to draw from, this is possibly going to be too much of a pain. Carriers could just be more expensive than battleships in terms of maintenance. I don't mind fighters being auto-upgraded, repaired, rebuilt, but this should be exposed to the interface, i.e., if you click a carrier, you should see that it has 4 fighters, can repair/rebuild/refit one at a time, which will take X number of ticks. This way, a player would KNOW what is going on, without having to micro-manage it, and if you advance in tech, it would mean that there is a certain lag before you see the better fighters, as it takes time for the carriers to refit them one at a time.
Movement points should be penalised for larger hulls or more mass, as surely 1 ion engine on a battleship shouldn't give it the same speed as 1 ion engine on a tiny hull? Sensors should get significant diminishing returns on being stacked. To attack should require at least 1 movement point, but should consume several movement points. So while ships with lots of movement points might be able to attack 2 or 3 times a turn, no ship should be able to attack 50 times a turn because it has over 100 movement points.