There's another example of how we learned the hard way to do what should be done automatically. You shouldn't have to care that your song is a file on your system. You should just know the song, and delete it through the application you use to manage your songs.
Nor would the redundancy of storing the same files once in the computer’s drive and also in the iPod.
One, this way you don't lose your songs when you destroy or lose your iPod. Two, the smaller iPods can't handle most song libraries. Three, synch times would be much longer if songs removed from the iPod had to be copied back to the computer, unless you're actually wanting to delete your music. And then it would be confusing -- did I want to just take the song off the iPod and put it back on my computer to make room on the iPod, or did I really want to delete the song forever?
Besides, iTunes isn't meant to just manage your iPod. You can listen to songs on the computer or stream them to other computers in your house.
Well, I know now! Lol!