Agreed. It seems that the Leap, being limited in its field of view, forces the design of UX utilizing it to strike a useless middle ground between broad and fine movement.

However, I've started to experiment with combining the leap with a mouse--i.e. left-hand over the leap and right-hand on the mouse--to control a single hand grabber/toucher/pointer object. I assign broad movements to the mouse and much finer movements to the Leap. It seems to work well, in much the way that arms work for large motor control and wrists work for fine motor control.

I concur. I got a Leap Motion, hoping to use it to replace some or all mouse function. It's a fun toy but not much else.