Reward Incentives for Doing Content Properly.

[Dewslam]

But if we're just discussing the idea : why not also grant the moogle tomestones on old raid with condition of no echo and min ilvl ? With a bonus for first timers ? Moogle tomestone farm events worked quite well to populate old content, otherwise it wouldn't have had 3 iterations, and the rewards are not crazy jealousy inducing, just a nice to have, that could be what OP is looking for.

Novel idea: they could hand out older moogle tomestones for older content!