I get where you, Dean, and the others are coming from. If the Wii were the only system I owned, I would probably feel left out in the cold. But as a supplement to my PC, it's perfect and offers the least amount of overlap compared with owning a PS3/360, 360/PC, or PC/PS3. Sometimes, I want to kick back on the couch with old favorite franchises and co-op through a Donkey Kong or Mario with the kids, and the Wii lets me do that at an affordable price.
But does Nintendo need to step it up with the Wii U? Yes, primarily in garnering third-party support and hammering out both new franchises and strong entries in their existing core series. So namely, the library of games needs to be much stronger this time around to ensure success on the level of the Wii since lightning may not strike twice with the casuals. That is, it COULD sell very well to the same target demographic that the Wii did--or it could flop with the moms and pops. We just don't know at this point. I'm leaning towards it having some moderate success in that area, though iPads and the like may have gobbled up some of the potential buyers.
Still, speaking on a strictly personal level, I am satsified with the Wii's library. I have too much to play and not enough time to play it--I haven't even beaten Skyward Sword, Metroid Other M, A Boy and His Blob, Monster Hunter Tri, and several others from Christmas time. That's not to mention the games I haven't bought yet--Sin & Punishment, Super Mario Galaxy 2, Kirby's Return to Dreamland, Rayman Legends, The Last Story, and Xenoblade. There is a lot out there to play, provided you have another system for the big-time franchises that skipped the Wii. At the same time, I understand that a lot of gamers have more time to play and different purchasing habits than I do, and as such their gaming desires wouldn't be satiated by the Wii's library.