As has been said plenty of times, Nintendo tried to preempt any advances from MS and Sony into the "casual" territory with the early Wii Motion Plus reveal and such. That's why there were so many core games at the October conference, those had to take the backseat to defending the territory at E3. Obviously the whole defense ended up pointless because MS and Sony preferred to pretend the Wii doesn't exist. It was a critical time, had either of the other two made a serious advance with Nintendo unprepared that could have cost them the market. But yeah, that's off-topic. The GDC is about development, not game releases.
I really hope Iwata will give the devs a talk on how to make successful games on the Wii because it seems there's tons of people who need to learn that.