It does makes sense, though. It would allow for more awesome stuff like:
-Stealth Attacks: The usual x2 damage or insta critical attack.
-Flanking: Attack something from the sides or the back = More chances to hit and/or damage.
-Other Senses: Smelling and Hearing could be made even more important with this feature.
I have played Unreal World and something like this isn’t as bad as most imagine. It would definitely improve the “survival” aspect of the game, in addition to allow you to stalk enemies yourself.
Coding it into the game is another story. 