I think you should consider the ability to buy merit for yourself. You can already effectively do this by way of purchasing a copper membership. Based upon the fact that well under 1% of active users have received a single merit, there need to be additional ways for people who do not post garbage to rank up.

Further, if people are buying access to additional features such as signatures, they have an added incentive to not post crap, and the cost will serve as a deterrent to those who have ranked up from posting complete garbage.