Deg's right in the sense that it's up to these third-parties to save themselves. I mean, NINTENDO is doing fine. NINTENDO is servicing their userbase exactly how they want to, and making money hand over fist in the process. If third-parties want to ignore that, it's their business. I would say "bad business", but not being on Wii isn't necessarily a bad thing for every company. Some companies just aren't interested in making Wii games and don't like the console, period. And that's fine.
Now when comparing the DS to the Wii, the DS didn't have jack for games - first-party or otherwise - until what I call the Great Christmas Flood of 2005. That's when you had Mario Kart DS, Animal Crossing: Wild World, Sonic Rush, Castlevania, and a bunch of other big games released for it. That was a year after its release, and only later did we see other stuff like New Super Mario Bros. and Zelda: Phantom Hourglass. The Wii has been quite different...it seems that Nintendo has blown their wad in terms of big franchises in the console's first 18-24 months of existence. Zelda, Mario, Metroid, Mario Kart, Smash Bros., Anijmal Crossing - they're all out there. I'm not sure where the Wii goes from here, but you gotta think that, like the DS, since Nintendo has "seeded the field" with their first-party stuff, that more and more third-party developers are going to make their way over to Wii. It's just going to take that one company taking a risk (like Square-Enix) and the flood gates will (hopefully) open.
What irritates me is that it seems that companies like Vicarious Visions are doing more daring things with the Wii platform than Nintendo itself.