<i>There shouldn't be any real reason to remove this service, nor will it help, especially if you're not on a local network.</i> --crono_logical

If you use a cable modem or such, you can get Messenger spam. My mother's computer would get those until I turned off the Messenger service. It's a fairly recent method of spamming I think. Way worse than browser popups, since it makes a pop-up error-type window and grabs focus immediately and it doesn't care what you're doing, it'll interrupt you anyways.