Depending on how you interpret the blue ocean push this E3 wasn't actually an abandoning of that concept but the realization that the appeal to the expanded audience exists in more than just mii-based small games. Malstrom keeps calling the blue ocean approach of Nintendo a return of the old school. Games like Mario Kart and NSMB Wii are selling huge despite being far from the traditional view of casual games so there might be something to that. Nintendo is realizing that the NES appealed to large parts of what is now the expanded audience (the lapsed gamers and many who missed the gaming wave back then) and that it's not the traditional gameyness that's keeping them away but some parts of the modern game evolution. DKC and Kirby are both 2D since NSMB has shown that NES-style games appeal to the expanded audience as well as the current core gamer.
Food for thought: Back in the Atari era games weren't yet stigmatized as entertainment for young males, videogames were for everybody. Over time that changed, probably with the whole "Sega does what Nintendon't" wave where consoles started competing over edgyness and went all out focusing on the young male demographic.