Fun idea, but has issues. The main one, for me, being that all guns point where I do. It seems mostly pointless to add more gun when they all fire at the same exact spot and I could add upgrades instead, which can surround my guns to keep them safe.
I'm being attacked from all sides, I want to be shooting in more directions, but the game doesn't allow for that. If the enemies were slower and less numerous then I could see precision aiming being more of a main mechanic.
Other games balance more coverage by having the player struggle with bullet coverage VS bullet potency. I think this could benefit from that struggle as well.