Aside from the carrier attack mode, all the other modes involving carrierse need spawn protection!
I had a situation today where we had 2 enemy gunboats sitting on the front side of the carrier in a way you could not kill them from above. You could not start a single jet or helicopter because they constantly shot everything down. Normally it shouldn´t be a problem to remove them, but most people simply don´t care to protect the main spawn and let´s be real here, they shouldn´t!
Worse we had an enemy jet flying around the carrier killing every air vehicle too!
In BF 1942 you could drive the carriers yourself and they had anti air turrets you could use yourself to defend the carrier. I am well aware we will never get this back, but at least make the carriers a spawn protected zone then. In BF 3 we had carriers too on some maps as a main spawn zone and they WERE!!!! a spawn protected zone!
Furthermore right now enemies can drop on the tower of your carrier and there is NO WAY to get up to them there to kill them. At some point we had 3 people sitting there, one witih a spawn beacon, one supply solider and another one with an AT4 killing all the ships which tried drive away from the carrier. Or they shot at the helicopters too!
If you give people the chance to act bad they will take every chance to do it, simply because there is no punishment for their actions!