>Hitman is an example that contradicts your point about gameplay, guards will see you in mirrors and act appropriately.
See:
>It's something that's trotted out as a nice gimmick, 99% of the time it's not there, and you don't really notice that it's missing.
Yeah, it's a nice detail for the 1% of time that you're in a bathroom or whatever, but it's not like the immersion takes a hit when it's missing. Moreover because the game is third person, you can't even accurately judge whether you'll be spotted through a mirror or not.