Motions like using a mouse or a keyboard are not a single bit more intuitive for flying planes or shootings guns. It just an issue of familiarisation with the interface as it was with the mouse, as it was the keyboard.

Beside that, it really doesn't matter as these were only two examples of a large variety of possible applications. If it doesn't fit the need - don't use it. There are other interfaces. There is no need for one interface to rule them all but for interfaces that really hits the spot for particular applications.

Regarding Leap: Looks really promising. Though i would prefere if it would be "hidden". Anyhow, can't wait to get my on it. Or over it.