Many third parties put time and effort into their games.  Come on now.  Don't generalize.  And remember, there's indavidual groups and companies inside those Thired Parties.

Now, if you're saying many Third Parties don't put a lot of effort into their games on the Wii, then that's totally true.

LOL

Nintendo only release the game when it's done, while many other are "forced" to release pre-maturely.

When you play a Nintendo game, you'll notice little details that were not totally needed but they are all there to make the game experience better.

I believe this question has to do with sales, and why does the Wii end up having so many more game sales of games by Nintendo, as opposed to other companies. On this, I think one needs to look at who Nintendo is, and their strengths. To this end, we are looking at these facts which may explain things:
1. Nintendo is the oldest console maker out there, and has years of experience doing this. They have been around awhile and have a good pulse on the industry as a whole. They sense trends better than both Sony and Microsoft, in this niche, and have things set up that they are now first. The fact that the portable market is theirs also, allows them to be a leader, do an evolution in this niche to test trends also. This being around longer has also forced Sony and Microsoft to cater to third-party game makers more, who have been in the business longer, and help promote their products. Nintendo doesn't need to do this.
2. Because Nintendo has been around awhile, going all the way back to the 8-bit days and arcades even, they have the the most popular mascot out there, Mario. Mario dates back to the original Donkey Kong game. Nintendo has leveraged Mario to launch new game types on their systems and establish them as franchises. Because of Mario, they are able to get a Go Kart racing game established. They also come up with a casual friendly fighting game. They also use Mario to introduce new characters and make them iconic. And then spin them off. This gives them an advantage over just about anyone else. Because they have their own system, they are able to do what Namco wasn't with Pac-Man, that being to entrench Mario everywhere. In this regards, Nintendo is the Disney of videogames, with an unfair advantage in the recognized character front.
3. Nintendo keeps rolling out new controllers and devices and has jumped on the casual game market in a big way. People look to them to see what would be new. And they bundle games with these new controllers, resulting in every system sold coming with Wii Sports, or done like Wii Fit. This drives up sales of their games, and puts them on top. They also likely have a better grasp on how to use their controllers, resulting in games that fit better and are more appealing. Throw in also unique games into the mix they launch and beat everyone to for the most part. Third party doesn't know what to make of what Nintendo has done. I believe they interpreted it all as customers supposedly wanting mini-games.
4. Being a console maker gives Nintendo extra media coverage, and causes people to look to them first.

I may of missed a few things. But a mixture of all of the above, and possibly some other things I have missed, are why Nintendo first part leads in sales. The fact that Wii Sports is bundled makes for no company able to beat them, as every Wii that is new comes with the game.

SMG had this in spades

Ice skating mario, how about when mario jump spins and he actually points his finger out, headlamps and breaks on the red shells underwater. so many details in that game

Effort.

Lots of interesting, provocative and insightful responses. Thanks! You know how you are, just about everyone who's posted so far.

My own perspective has been shaped over the last year and 1/2 by the thoughtful members of the community and a particular blogger named Malstrom. Although I've taken a lot away from my readings of his Malstrom's essays I've also noticed that his analysis can be very sloppy and he's often too vigorous when he need not be and not vigorous enough and simply bypass a point that needs a trifling bit of logic. That's why I love the thoughtful posters here, they work the realism back into the theory.

Some posts that have led up to my current views are these:

Short version: AT E3 2007 it was obvious Nintendo was going back their Famicon roots by showing off games that people would enjoy playing and devices that would supplement that enjoyment. The Wii Board, once unveiled, became the ultimate long leg monster of Famitsu and NPD charts.

Nintendo's focus is on making entertainment for people. Some game makers are motivated by the challenge of creating a fun game that everyone can enjoy. One of them works for Nintendo and his name is Shigeru Miyamoto.

Nintendo has always been very good at establishing genres they get to define and profit from. That is because Nintendo, at it's best, comes up with games that they would like to play ang then create hardware to make it possibble. When Nintendo gets it right they make games that can only have the definitive version on their console. Games like Wii Sports, Wii Fit, Wii Play, Wii Music and Mario Kart.

I blame Wii Fit.  

it is oftuns vetter to leev this lost plsaec heir floklore has it that is someone destroys the thread by posting more then they are fates to die a slow painful death while alone. Each poster beyond the first adds the misery and becomes a new victim of teh cures. But heh, that's just me.

I know sega published it but that hardly counts as a third party game. Take nintendo's backing out & maybe it's at half of where it's at now.

I remember a comment from an E3 press conference by Nintendo, that their end goal is a smile on the face of the player.

one word : talent