"Why the heck is Nintendo bundling Windwaker HD with the Wii U, if they don't believe it will generate sales like a new game?"
Nintendo do not think The Legend of Zelda : The Wind Waker HD will match the Nintendo Game Cube version sales, but probably think The Legend of Zelda : The Wind Waker HD bundle will have an impact on Wii U which is between the Pilotwings Ressort and The Legend of Zelda : Ocarina of time 3D bundles on Nintendo 3DS.