They want the better quality sound that you get from a CD, which the MP3s just do not have.
Richard
I would tend to disagree. I defy anyone, audiophile or not, to tell the difference between a MP3 with VBR (Variable Bit Rate) encoding at 192 kbps or above, either on my iPod or on a decent hi-fi. Additionally, if you choose not to compress (both the iPod and your computer should be able to play the raw AIFF file) there is no loss at all.
I have already begun the move over to a fully digital system - I have begun shopping around for a new hi-fi and will not be buying a CD player
Jx