i've always been something of a military history buff. "combined arms" is the doctrine of mixing multiple types of combat units to create a more flexible, lethal team. think of armored cavalry today. you have armor, infantry, and even strike helicopters working together on the battlefield. to me, the multirole capability of a valkyrie in the macross universe seemed to naturally fit into that framework. hit the enemy with an airstrike in fighter mode, then get up-close-and-personal in battroid mode.