Nintendo doesn't really need third parties for the Wii.
Hell, Nintendo doesn't even really need to make new software: games they released a year and a half ago still chart. Wii Music, a POS game, has sold a couple of million and will probably hit 5 million when it is all said and done. Wii sales decline but I still think that is due to the fact that it is no longer a craze like it once was but it is still selling a few million per month worldwide, Nintendo doesn't have to worry. Nintendo doesn't need to worry about putting a lot of effort in their first party titles when Wii Sports Resort will probably hit 10-20 million copies worldwide. Why try? I'm still amazed we're getting Galaxy 2.
I think everyone understands the third party treatment of the Wii except for Nintendo fans, who think that they are entitled to amazing ports or exclusives of top tier titles. Developers obviously know the Wii market well - the poor suckers that make games that Nintendo fans claim to want flop. Unsurprisingly, the same Nintendo fans who really want those high scale games on the Wii ignored games like Dead Space. Better to make a pet simulator that might accumulate 500,000 sales than a well crafted port that sells 9,000 in the first month.
The downside of the Wii is the Microsoft and Sony solutions to waggle, which I think will fail and then be quickly forgotten, the same fate I expect will happen with the PSP Go.
I think this generation is kind of a wash at this point. Every system has at least a couple of crucial flaws and any attempts to rectify them seems to be more than a few days late and more than a few dollars short. I do want Galaxy 2 but after that, I'm just waiting for the next generation of machines at this point, although I realize it probably won't be until 2012 or 2013 until we get them.