It's just one of those things. Like how we have topics that end up drifting badly off into something completely different. ( email notifications anyone? ).
It could be people really don't have anything new to talk about. Or the existing threads already cover it. Or the people here don't post much up because they're more savvy than the average and don't need as much help. Could be people just don't have the time anymore.
Easiest way to get more topics is to post them though :)