I really don't get now at this point, why Nintendo didn't make this Mario Party online. Hell, why didn't MP9 have online. Even the most recent Mario and Sonic Olympic game finally got online multiplayer (though I hear it sucks.) I haven't owned a Mario Party game since the Gamecube days. The game is best with friends and playing solo leaves a lot lacking. And I'll admit I'd rather play with people with the same room.
But I do see if there ever is a Mario Party online, people dropping out when they start losing which is downright annoying in ANY online game. People did it in SSBB a lot.