I see your point, but I still don't think forcing someone to post will do anything good...
But it would be cool to have an active community.
You'd be surprised. In this day and age, the majority of people will only do something if they have no other choice but to do it to get what they want. People come here for the anime torrents. If they have to post to gain access, then the majority of them will have no problems doing so.
There will be much less that complain than there is those that would just willingly do so. And those that complain were the ones who would be doing nothing but leeching and using bandwidth, because they otherwise would never contribute anyways. So to people like that.. who cares?
You know the majority of the people that have joined the tracker would not have joined if they didn't have to.. but has anyone complained about having to? If so there wouldn't be that many... It's the same concept here.