First: I'm not a developer so I can help with suggestions and ideas only.
Second: I like the clean&fast style of esoTalk and I think that adding too many plugins could ruin it.
Third: anyway I think that a gamification plugin could be interesting for esoTalk and for Flarum too.
For example: every year the user gains a "year medal" that appear in his profile or receives a "like medal" if his posts are liked by the people and wins an "avatar prize" if he loads an image on his profile.
There are many gamification plugins (YAGA , Peregrine Badges ) that add these functionality.
Giving users badges based on statistics and engagement is addictive for a community: imagine a plugin that allow the administrator to create and award custom badges for special events and recognitions. For example: an user creates a logo for the community and the admin can give him a "thanks medal": this create affection.
Imagine Award Ranks which can confer different (configurable) permissions based on community perception and participation too.
I think that it could be very interesting a plugin like this, in the respect of esoTalk philosophy, of course.