CG, same on a ship, same in a plane, that historic attitude seem to prevail where everyone under the top man or behind the pilot has no control over their destiny. Over simplification I know but how many aircraft captains would press on if their rear crew was curled up in flak jackets down the back?
For my money I would not want to be a door gunner or an ALM standing on the ramp when everyone else is prone on the ground. I bet the Taliban shoot at the gunner not at the pilot.