The GameCube had many "megatons" too.
Resident Evil full franchise exclusivity is a bigger megaton than anything I've seen from any console maker the last few years. Metal Gear Solid remake, Tales + Baten Kaitos, Sega + Namco TRIFORCE arcade board, GOTY Metroid Prime, etc.
The core hook of the Wii U just isn't appealling enough to bring in casuals which buoyed the Wii IMO, I think what's actually going to happen is as the months go on, this fact will become more evident.
Nintendo can announce all the Marios and Zeldas they want, Wii Sports/Fit is yesterday's news, and that's the main problem for the system. They bet the farm on that audience coming back and didn't make a machine appealling enough to get the 360/PS3 crowd either, so they're stuck up creek without a paddle IMO.
