The reason is that Carriers are not going to be like either of them, but their own class. They will never have the firepower of either a light or a heavy battleship. Since they are supposed to launch drones from range, why not simply take the opportunity and get a heavy carrier that can launch heavier drones? If Carriers were like battleships, (4 heavies a heavy carrier, 3 heavies a medium carrier, 2 heavies a light carrier) we would ofcourse request a light battleship Carrier. But with the drone bays the heavies will be removed and only primaries will stay, hit points will be decreased. There is no use of a light carrier that will die to battleships of any kind that get in fire range. A heavy carrier, defended by heavy battleships, launching heavy drones behind the Valors is just more useful.
Also the Valor is already capable of fighting any BS-Class. No need for a light one.
