Holy crap, DEAL BREAKER. Are you serious, man? The only reason I own a Wii is to play Mario Kart 8 with a friend online. In fact, she bought me the system and Mario Kart for Christmas because we had so much fun playing Mario Kart Wii for YEARS together.
We've been hoping to find another fun online game to play and I figured this may have been it, but I can't believe that you can't be guaranteed to be on the same team when you invite friends.