I don't get it personally. I'd rather know my surrounding and also feel like if I wanted to i could easily get out of a game.
Getting out of a game is very easy, take headset off!
As for the first thing, do you have trust issues in your environment? Do you ever play a game or watch a movie with the door closed? How do you know what's going on behind the wall? I don't play with headphones though since my surround system sounds better, plus it allows me to stay aware of my surroundings. Sound is a much better way to stay aware, f*** people that walk/jog with headphones on!
I don't like gaming with headphones on for the simple reason that does cut me off completely. I can hear what happens behind my back, above me, in the other room. Unless your wife uses sign language to communicate, you're fine with a headset, not so much with headphones :)