Chat is a much different animal than the game thread. I really can't describe whether it's the format, the people, or that GAC is such a wonderfull human being. But for some reason it's just...different. So IMO it's harder to "clutter" or get too far off topic to the point of distraction.
Of course the nature of chat will change if suddenly 40 people are in there every night for the entire game. Will that be good or bad? Hard to say since that's never really happened before (at least in the year I've been here).
But chat seems to work better with more people, so it's an experiment worth trying out, IMO.