In an interview with Kotaku, Shigeru Miyamoto says, "While online play is certainly technically possible for us, it simply wasn’t the focus for us this time around. What we really wanted to do was to create something that people could experience fully while playing comfortably with others who were nearby them, and this is something we decided would be best for Pikmin and the best case for Mario here as well."
It's understandable what Miyamoto's intentions are: create an atmosphere that can only be found in the living room.
But does the approach have to be either/or? If Nintendo can make successful online multiplayer first-party games such as Super Smash Bros. Brawl and Mario Kart Wii, and yet can still have these experiences in the living room, why can't the same be done for Mario Party, the Wii party games, just to name a few?
By eliminating the online multiplayer potential, Nintendo is arguably restricting its consumer potential, and its argument for bringing back the hardcore gamer has probably been diminished. Only time will tell.