Given the track record of MMOs the odds are any new MMO is going to fail -- after all, out of dozens of MMO launches only a handful are still around today, and only one has really achieved breakout success. All have had great teams, funding, personalities, etc but failed in some of the very basics of the game or replay value (AoC, Matrix, Tabula Rasa, Fury, POTBS, etc), not because they didn't support multiboxing well. I'd put multiboxing support in the same category as supporting blind/deaf/etc users -- put in some basics to not shut it out, but its something you can iterate over even after launch, not something to focus on during design.

Sometimes having too many "great" people is actually a bad thing, since you end up with decision paralysis and no clear decision leader.