It wasn't just about the power.
Since Nintendo had to prove themselves once again to a certain market, launching at the same time with =/> specs to the competition wouldn't have mattered. What Nintendo needed to do, was copy the 360, and take advantage of the year head start as the lone, true next gen console. This way it has a chance of "stealing" PS360 fans (the not so hardcore but need 3rd party fix) that were tired of the extra long generation.
If Nintendo released Wii U or Wii 2 with XB1 level specs (maybe gamepad sold separate like Wii fit, give it a chance to become popular not forced) it would have done FAR FAR better. It definitely would have bit into PS4/XB1 sales. PS4 would be closer to 15 mil sold and XB1 sub 10. Nintendo at the very least, would have around 17 mil.
