Yes, because on a touch screen the keyboard is on the screen where you're looking anyway. I would never in my life use a projected keyboard on my desktop/laptop. Touch typing and tactile feedback.
I wonder if anyone has done work on some kind of chorded keyboard input just from touching fingers to your thumb - that could be done with some kind of sensor gloves and seems a pretty natural motion.
Might be quite tricky to learn though!
Edit: I see that Magic Leap are working on sensor gloves.