Imo, and I could be way off base here, the reason the IGT threads are not very active is because a couple of posters who made things "interesting" have pretty much left. The posters I speak of usually had very different takes on things, which caused a lot of petty arguing, etc. One in particular usually stirred things up to the point of making each IGT probably 3 or 4 pages longer than it would be without him, hence, the shorter IGT threads. Again, this is just an observation and opinion.
I also believe that another reason the IGT has less traffic is because the posters who have felt the need to police it have turned off some of the regulars from the past. I know this for a fact, but it is what it is.