I guess the potential problem I'm trying to point out is that you run the risk of making large numbers of characters beholden to the whims of a single player. What if you have someone playing Batman that doesn't post very often but has plans for Killer Croc four months down the line? Should they take precedent over someone that comes along that desperately wants to play Killer Croc and will post three times a week?

In that instance I'd sooner have more players, even if it results in differences of opinion in terms of direction, than fewer players. After all, this isn't fan-fiction. Interaction is kind of the point.