The forum is very new, it is normal not to have many many threads.

I do not think that it would be a good idea that thread starting to be compulsory for the members.

Now you can make 5 threads per day. That should be enough, to avoid flooding.

Why people consider that replying to the existing threads it's not enough, and that everyone should make as much new thread as they can?

I consider the replies more valuable than creating new threads.

As time passes by, there will be more and threads and replies... just give the forum time to become mature.