I think the problem with Harry, as has been pointed out, because of the nature of the enemy he is too big a target in his own right and would actually cause serious problems to the Army he serves with. Charlie was a captian in the tupperware navy who by thier nature were not involved in NI, when Charlie was doing his main stint.
As for the other royals. They are figure heads e.g. Colonel in Chief, of many regiments. The role is symbolic, and historic, and important to the regiments, even if not to some of those who serve.
But politicians who just fly in and fly out should not get a gong. They sould be like others and serve a tour of duty in a war zone in order to get the gong. It is also important to remember that there are two types of medal. Those for being there, and those for valour.
Many servicemen and ex-servicemen I have known have been a bit embarrassed with gongs for just being there.