from my experience when playing co-op, it seems there are mixed feelings about the mini map.
Personally I always play with the mini map enabled and I tune the options so the overlay is more visible.
I mostly do this to speed through the map killing mobs and doing the objectives.
However, every mission the mini map needs to be manually called forth (on the ps4 with the d-pad).
Every time a conversation is triggered, or a clue, or a video, or when you use a teleporter, the mini map overlay is gone and must be called forth again.
It is by no means an issue and definately not game breaking.
However, being a fervant user of the mini map and playing many missions, this has become something where I feel that an option to enable the mini map by default would be awesome so that when starting missions, using teleporters etc... never turn the mini map off anymore.
The only reason I suggest this is that it would increase the fluidity of play and disable 1 thing to micromanage :)
My thumb would be greatly appreciative for a feature like this :p
This is just a personal thought and by no means a big issue at all.