I would abstain from complicating the user experience, though. In my experience, posting a topic has much more potential in gaining points than writing *thoughtful* comments. A good strategy to rise above that ranks is to post a bunch of interesting links; upon achieving high points, the user can then take a defensive stance by defending his or her opinions through posting comments instead.

The point is, from a user's perspective, there is more to gain from posting topics than comments.