You say that like it's a negative. You don't have to ever detach from the TV.
The real upside to this is that the split development of Console and Handheld will be over. All the best people will be on the same team working on, say, a new Mario.
I suppose that's a fair point, but they can only cram so much power and hardware into a device that's designed to be that small. I'm skeptical.