Moderators can comment on flags. Especially if they suggest the flagging user does something, it would be helpful if that information had a way of reaching the user.
For example, I got a flag suggesting migration declined, and a moderator commented:
declined - Question is fairly low quality at the moment and relies to much on external content. Maybe you could edit into shape.
I stumbled on that comment (on which I'd have acted) only about a month later, when the question was already closed, and sort-of answered. A notification would have been very useful here. Would it be possible to add that feature?