Yeah true, In these days most new members are join this forum only for bounty campaigns. They are trying to rank up their accounts quickly for only bounties. That's why bitcointalk added a merit system. I think this forum rules will be more high in future.
Yes, I think in addition to fixed number of merits to reach a rank, there should also be a requirement to earn some merits very year to maintain rank. This should be enforced for senior rank members first.