You're completely missing the point if you keep thinking that the motion controls are meant to be used for games like "serious sims".I did, and ruled that out almost immediately. You might as well point with your elbow. Besides, have you ever done that warm-up excercise where you move your fully extended arms in decreasing and increasing circular motions? You wouldn't last 5 minutes.
Now, I was going to let them pass, but purely out of a fickle sense of spite at the bold(), I'd point out that your tilting the head to control the camera would never work or be allowed in a game, let alone in favour of the right stick. That'd be like trying to aim using the Sixaxis tilt. Grenades would work well I'd have thought too, and being able to look around corners by tilting your body would suit sitting in a seat as well as standing up. You're far more likely to see the game use your head movements subtly to give a sense of depth to the onscreen image.
Similarly using your feet to control a football in a serious sim would be simply awful. Fair enough for a party game or something casual, but never in FIFA or PES. At a push I'd say free throws in basketball would be better suited, but it's still hard to tell without knowing what the accuracy you can get from throwing would be like compared to real life.
I don't see why head tracking would never work or be allowed in the game. It worked decently enough on low-res cameras on low-end PCs back when Matrox was pimping it for the PC years ago. It could be used to cool effect if calibrated correctly and not requiring large tilts.