Currently, the only time (even in Human vs Human games) a carrier is actually useful is on large maps (and even on the largest maps, it's pefectly possible that the two continents are well inside bomber range). Not only cities can't be sunk, but they can house way more aircraft, air defences, and especially stealth bombers)
So, here is an handful of (not very hard to implement suggestions to improve carriers)
A)The carrier is transformed into a super long range artillery unit, to stimulate a air strike. The carrier also provide a wide area air defence. Carrier strikes are especially mortal against ships.
B)The Carrier can ferry aircraft, but the only aircraft that can make strikes from a carrier deck are either a new fighter type aircraft (called CAG) or an fighter aircraft that took a promotion (say, Naval Air Training). CAGs provide excellent air defence and are deadly against ships.
So, here is an handful of (not very hard to implement suggestions to improve carriers)
A)The carrier is transformed into a super long range artillery unit, to stimulate a air strike. The carrier also provide a wide area air defence. Carrier strikes are especially mortal against ships.
B)The Carrier can ferry aircraft, but the only aircraft that can make strikes from a carrier deck are either a new fighter type aircraft (called CAG) or an fighter aircraft that took a promotion (say, Naval Air Training). CAGs provide excellent air defence and are deadly against ships.