The problem is that Nintendo tried the core gamer approach for years, and it worked until the 64. Then the GC came out, and was everything a developer should have wanted; 7 buttons, lots of power, internet capable, and the best copyright protection available to the disc format. And how were they were rewarded for that? Being called kiddy and pretty much abandoned by 3rd parties.
So with the Wii, Nintendo said, screw you, we're going to do things our way and prove we still got it, and they have done it. Not in a way that we as core gamers like, but nonetheless they have proved their worth when every was saying they should become like Sega and only do games. Their 'core' games sell like mad, right alongside their casual games. All that's missing is 3rd party developers who had been ready to write-off Nintendo.
Despite all of our complaining and doubt, the Wii still sells strongly, so what reason does Nintendo have to change strategy? Why go crawling to people who didn't want anything to do with their system until it was sold out for two years? Especially when they've manged to do well without them.
Personally, I expect Nintendo to surprise us with the Wii2 just as they did with the Wii, and push the system on that innovation and the promise of great games, just as they did with the Wii. 3rd parties are in third place when it comes to priorities for the Wii2.
I know they consulted developers on the 3DS but I still think that was in response to the recent successes of the PSP and that people are much less likely to have two portables, while buying a Wii for Nintendo games and another console for everything else isn't farfetched.