I use Library Server so that only one PC (the server) tries to maintain the library and playlists while the other 5 PCs can use it to play music elsewhere in my house. I used to have each PC point the library to the same network folder but then each MC install would try to maintain the files which was problematic.
I'm sure that other more sophisticated users have more reasons to use it but these are mine. I would be very unhappy if Library Server disappeared.
Craig