This is a nightmare for AFV crewmen. If you are not looking down the sight, and the vehicle turns in another direction, the gunner will have to traverse the turret onto any appearing targets once they've entered the primary sight again.
From a commander's point of view, it is a hassle when hatch down, as when going from using the vision blocks to entering the commander's sight, he will have to once again traverse his sight onto the target after looking down it.
Possible solution, allow stabilisation options (such as when turned out, outGunnerMayFire) for when not looking down the sights.