There is the nunchuck btw, apart from the IR sensor it has exactly the same motion sensing as the remote.
I understand where you are trying to lead, but as you said near the bottom, there are many limitations, and also certain genre have many needs that would not be satisfyed.
I do think that any sequel to Zack & Wiki will hopefully use both Wii remote and nunchuck, which may come close to what you have envisioned even if only for the little scenes where you interact.
I think I came somewhat close to what you were thinking with my idea for an in-depth racer... This is the control scheme I thought of:
Wii remote held in Wii wheel controls steering.
The nunchuck is also plugged in and due to its small size you can hold it in your palm with your fingers holding the Wii remote/wheel.... whenever you have to change gear you can release the remote/wheel with your nunchuck hand and perform the specific motion: like if going from 2nd gear to 3rd gear you would move the nunchuck forward->right->forward.
The balance board could act as the brake/accelerate pedals as well.
