Due to the close proximity of the escorts (DEs) and the carrier, the difference in over all range if all the escorts had their own radar would be inconsequential. During the war, radar equipped destroyers would be sent to take up station many miles from the main body of the fleet, along the likely threat axis. That's how they insured sufficient advanced warning of an incoming raid. They were also horribly exposed, and suffered disproportionately higher losses than ships of the main body. Since there is currently no way to task an escort to move to a picket position, I don't see this as a particularly effect change. The single radar platform of the AH CV fleet puts it on a parallel with what the land bases currently have in the game, but with the added advantage of being mobile. One base, one radar station.