I primarily play stealth characters but I honestly wouldn't use this feature. It's a priority thing. I would think there are better things they could spend dev time on than this. Plus as you said if they didn't start with this in mind it might not work out well anyway.
I really dont think this would take too long to do, but I'm not a game designer so i might be wrong
and i think it probably wouldn't work out well if they added it in at this point, like i said, but again i don't really know i'm not a game designer