Yes it makes sense. I was actually thinking about using the listeners as a way to inject/cache reference data. So instead of using @DbRef, which is going to be deprecated anyway according to the MongoDb team, I'll just use the ObjectId.
--> Has a list of Roles
I don't want to embed these global roles (e.g. System Admin), So I link the ObjectIds instead. Roles is also something I want to cache on the server. When a user logs in, I need to "enrich" the user with the role objects that I put in the spring security context. The listener, then, should ,onAfterConvert of User, look first in the cache to see if it can find the roles. If it can't find it, it loads it from mongo, sticks it in the cache and adds it to the user. This "enrichment" process might not be necessary for all calls to load user either.
The problem is I cannot inject any other mongo repositories into the listener as the repositories haven't been created yet. So I basically had to stop using the listener and do it manually.
I think using the listeners in such a way would be pretty useful for people.