For any given player direction (where you go when you press 'w') you can move your head by about 165 degrees to each side and your weapon by about 15 degrees without causing your character 'direction' to change.

If you clamp the auto-orientation of the optics to never exceed 15 degrees to each side I would agree with the proposal. The situation WarRemains is talking about is where you can be following someone and their head is pointed at you but their back is turned. Then they auto-orient, instantly rotating their body, and blast you.

You didn't consider the value of the way the current system is set up though. It's designed to where you can anchor your weapon/binoculars to the most pressing location. you can examine your surroundings for awareness but you never want to lose tabs of what you were initially looking at(a specific bush in a forest).