I read your post and tested your hypothesis I made 2 topics to see if active discussions could be initiated.
In Off-Topic I started a topic about JCVD's latest flick Universal Soldier (and the series in general), and then for Gaming Forum I made a topic on Super Street Fighter 4. I think both topics were discussion worthy and not discussed on the forum before but appropriate for our demographic, yet both topics discussion ended with in the first day, this post is made around 72 - 96 hours before the topic was created.
Results: Forum Dying
This forum is now a very
small community. Trying to discuss very specific things is never going to make a busy thread here because anything that interests less than 50% of us is not interesting many people at all. A good example is myself: I have never watched the Universal Soldier movies and I don't like Street Fighter so I didn't click on either topic. I wouldn't on a busier forum either - it's just that me not posting in a thread makes more of a difference here.
We all know this place isn't as active as it once was, but the point is that the people who still come here probably won't be leaving anytime soon. Your 2 threads created 8 posts that wouldn't be here otherwise. If we all did that, it would be a lot more posts everyday. If you really want more replies though, I'd suggest more open questions.
I have never heard of Universal Soldier before... I clicked it and I didn't have any interest in it, so I moved on. I don't have a console that Super Street Fighter IV is on, so I just skipped that one.
Also, you can't just create threads that say "Hey guys, let's discuss topic X." You gotta have a point to them because I had no clue what Universal Soldier was and you didn't give me much reason to stay in that topic.