I think that the decrease in merits receives is due a lot of the non-merit source users have exhausted their sMerits to give while some are still keeping their sMerits as like what you have said earning Merits is now pretty hard. During the first few weeks of the ongoing system we saw a lot of users sending 30 to 50 sMerits (which is the maximum a member can give to another user) to worthless post but the bright side of that is they become a suspect for cheating the system and was tagged immediately by some DT members.

Even with the lack of merits to give I do still think that there is no need to add more merit-sources for now as we still need more time for the merit system to do its thing which is to reduce spam and create more sensible post.