(Ok... I searched before I posted to don't flame me too hard if I am duplicating)
Ok... so cars/trucks/minivans/etc have had rear facing cameras in them for years now. And before that we had rear view mirrors that gave us some (semi-obstructed) view. Heck, my new-to-me truck even has a forward facing camera when it came from the factory!
Sooooo... how about a *functional* rear view "mirror" or camera for my mech? I don't care if its an internal or a purchasable upgrade or what ever.
Some of you will say "radar tells you they are behind you" and I agree but it doesn't give you more details than "behind" where as a "mirror" would tell you if there are any obstructions or if they are at ground level (in the view of the "mirror") or if they are up above you (Radar says behind you, "mirror" is empty.)
And to further bolster my point, do a google image search for "fighter cockpit mirror". You will see plenty of example of "modern" fighter jets that have rear view mirrors in addition to their sophisticated radar and flight controls. (This picture of an F/A-18 has three, one top and two sides)
Lastly... as has been mentioned in other threads, I can then also hang my physiX fuzzy dice from them!