When Ive seen it on other sites, its been more of an off topic type thread.
I dont think it harms any of the normal traffic or action, and most of the time its viewed in the same category as a joke thread, or "whos your favorite hockey team" kind of thread.
Ive never seen it reflect poorly on a site in any way either, since its always been in a off topic, or sometimes a club member (member donation) type area.
However it wouldnt break my heart if there wasnt one here either. I personally come here to learn about wii stuff, and I have other forums for BS'n on, and other crap like that. If this forum stays more of a strictly wii type forum, then an all around "all topic somewhere" forum, that wouldnt bother me either