Thing is, Nintendo admittedly made the decision to stop being in such direct competition with Microsoft and Sony as it used to be. And sadly, it works. Where the GC was arguably the most powerful 6th generation console around and suffered only from its lack of strong third-party support, the Wii is the same decent 6th generation console in a world made for 7th generation consoles, with a few flashy new perks tacked on. The targeted demographic falls in 3 large groups, which is one of the reasons it's selling so much.
1- The Nintendo fans who have been expecting the next Nintendo system for a while, would have bought it no matter how it was, expect next-gen entries into their favorite franchises, and actually think they own the Revolution.
2- The gamers who don't know too much and saw an opportunity to own a next-gen system for half the price, and think next gen merely means a system that will see new games for another 5 years or so.
3- The so-called "non traditionnal gamers", the moms and uncles who find appeal in the casual games.
Likewise, the games fall into 3 categories:
1- The first party lineup (Zelda, Mario party, Metroid, Mario galaxy, Super paper mario). Mostly these were planned for the GC and would actually worked better on it, since they don't have anything that couldn't have been done on the GC, except with Wii controls added in some form or another. The exception to this rule would be Galaxy, of course.
2- The multi-platformers (anything published by EA, Ubisoft or Activision, and anything based on a movie). The Wii version is usually the weakest one, since the developper doesn't have much experience with the system and doesn't want to waste much time learning it (time is money, folks).
3- The casual games (Rayman, Carnival games, Mario party again, Playground, Warioware) and the games that come out at 30$ or less (anything by Human Conspiracy, these days). The strategy here is to flood the market with as many games as possible and hope that you'll make more money than what you've spent in developping costs.
As we can see, Nintendo has more 3rd party support than it used to, but still lacks *good* 3rd party support. And with the first-party lineup being 5 years too late in technology, the situation is actually worse than with the GC for anyone who doesn't fall into fan groups 2 (low-budget gamers) or 3 (mom and uncle casual gamers). So apart from the 1st party games, what else was good on the GC? The unexpected hits in the form of 3rd party exclusives (RE4, Killer 7, Tales of Symphonia, Eternal darkness), and to me that becomes the sole interest of the Wii so far, which is why I actually bought another next-gen system right at the beginning of the generation this time.
Now, Sony used to have good 3rd party exclusives, but it's lost exclusivity to most of these franchises (Devil may cry, Silent hill, Ace combat) since Microsoft is willing to pay for exlusivity (Bioshock) while Sony's not, on the other hand, Microsoft delivered too early with a system that wasn't technologically reliable at first, lacked some important features (HDMI ports and wireless networking come to mind) and put much emphasis on the paying live services. I think it's going to be a pretty bad console generation all around, sadly. Just my two cents.