My music library would be a complete mess if I did not let iTunes manage the folder. Keeping over 12,000 songs organized manually would be a monumental task. Though I only let iTunes sort the Music library not copy music. Rather I will just create a new folder in my music folder with the date. Then have iTunes add the folder to the library. At which point it will move the songs into the appropriate folders.
I also keep my music folder on a separate volume. Once all the hardware comes in, it will be offloaded to a dedicated server with all my DVD's so that all computers use the same music library. Too bad they can't all use the same library database, each time a Mac or Windows computer opened it one would have to wait quite a while for it to rebuild the database file.
I really wish Apple would make an iTunes Server edition though. So that any additions or removals from the Library are reflected on all client computers yet each user can have there own playlists. The iTunes Home Sharing is worthless as it actually copies the song over thus making duplicates all over your network.