Yeah, early on they talk about the genesis of the hardware design for the Wii Console, and it sound much like what you suggest Big Jim, that their genesis was really the urge to do something different from simply throw more specs into the hardware. Where this urge came from one can only speculate, whether it be a prescient Iwata or a realization that compared to Sony and MS, they had to do something different.
Also, it seems that there were also several different motives within Nintendo that drove them to the Wii's present form. They were already intending to get motion control in the controller, but even as early as merely implementing it in a traditional one-piece controller: motion-sensing was a concept that predated the Wiimote.
Also, I think someone mentioned getting their grandfather to play on it with them, and how isolated playing games makes them feel compared to the world around them, an impetus which manifested not just in interface design and Wii channels, but also coincided nicely with where the controller was heading independently.
If we had DS development interviews then we might have a mirror to use to see if this was an internal concrete message by Nintendo to go blue ocean, or merely lucky coincidence!
~Carmine M. Red
Kairon@aol.com