Personaly I think you're point is irrelevent. Let me explain, you say you could guard the lazer spawn, right? but there are at least four guns on the map capable of killing the Banshee (lazer,bazooka and two snipers) and one Banshee couldent guard all of them. So there were enough options open to begin with, thats not even counting the opposing Banshee. So when you give potentaly every player in the match a power weapon, something such as a Banshee will lose its value and in doing so brake the flow and balancing of the game. So you're upside is not really a big enough one.