This is not a bad idea, depending on how it is implemented. A little benefit for those who play well -- and well with others -- would be a nice thing.

However, this of course will do nothing do deal with the problems of bad behaviour as there will be no negative repercussions for trolling, harassment, and juvenile actions in a DF group. The fundamental problem with DF remains: as long as it is not one-world only, where actions will have consequences and reputations will get made, it will continue to be something that keeps enabling the worst elements of the larger FFXIV community.