No support. I just don't want it. These ''not needed'' arguments are childish but yeah just don't want it.
Unneeded.. I wouldn't be curious about someone who unfollowed me because I obviously didn't mean much to them then. If it's someone close, I tend to look at their profile often enough anyway to keep the following/unfollowing, on track. That's it. Not needed.
No support. Lets say I unfollow someone by accident and I didn't notice, and they get all mad and they start an argument with me. I honestly don't see it as useful either. I don't care when I get unfollowed so I honestly don't need an alert saying that. I would be neutral if there was an option to disable the alert.