Ironic thing was.. WC 2, followed by WC 1 had the best cap ships (and fighters) WHen they switched to polygon shapes.. they just sucked.. but they were at the pinicle of technology then.. tnohing they could have done better. I would kill to have a WC 1 and 2 remake in current technology.
A good way to easily mod the game to make carriers more important is to make ship weapons require more supplies to use and make resource generators produce a lot less.
Also, decreasing the amount of resource production from facilities will increase the value of the carriers and fighters (since units don't require maintanance)