As Mulsiphix said, the current subforums allow those with specific interests (genres or game systems) to post questions, comments, and the occasional rant, without having to wade through other threads and posts. (I thought this was the point of "subforums".) The current segmentation may not be perfect -- what is Dark Future anyway? -- but it's workable.
The D&D Forum has the lion's share of traffic, because most people play D&D; all others pale in comparison. If we created forums purely to balance content in each, we'd end up with "D&D" and "Everything Else", which would annoy those of us who play something else than D&D.
For cross-pollenization, there's the "General Discussion" subforum under each genre, or "General Chatter" if all else fails.
"Campaign Resources" were, in fact, the precursor to Articles and Blogs. I'd be happier if they were apportioned to the appropriate place, but maybe they serve as a historical reference.
"On two occasions I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question."
- Charles Babbage (1791 - 1871)