The problem is that those possibilities don't make up for the basic functionality that it loses (especially if the motion sensitve stuff doesn't work 100% perfectly, rendering it useless for percise functions). It would be neat as a seperate, optional controller for some games, but as the main controller it has to work for a wider range of games, many of which won't be designed specifically around it.
Its simply isnt just a motion sensitive device. Turn it to its side its a classic controller. Attach the analog stick it becomes no different than any other controller out there, with no need for special programming for it. The device is an option for programmers not a mandate, it still has its primary function as a controller.