Well yeah, a good, friendly community is always a plus, but that alone isn't enough to keep my attention for long periods (months+). I usually end up practically abandoning every community I join, and rarely even reach 100 posts anywhere. I think the key reason is that most boards like these are specialized to one area, for example, this one is mainly focused on anime-radio, which may expand to topics such as anime or japanese music. However, as a human, I have many interests, and just one interest usually won't keep my attention forever... my other interests are better suited for discussion at communities which specialize in those, because I'll have a greater audience there. Even if this forum has sub-forums for those interests, it would be irrational to, say, expect the people browsing the video games subforum to have the same detailed discussions as people at GameFAQs or other specialized gaming forums.

Anyway, I kind of went off on a tangent there, but thanks for the response!