...they do it when you buy CDs, too.
I keep on complaining on how bad MP3s are, quality wise, compared to normal CD sound (16 bit PCM at a 44K sampling rate).
Alas, if only CDs really utilized the sound potential they have. Some of the later CDs we bought sound so crappy that you would actually prefer to listen to them in MP3, where a lot of the shit is massaged out, and not on your hi-fi.
Special worthy of mentioning shitty sounding CDs include recordings by the so cool Gorillaz; a chain saw has a better sound then their Demon Days album. And Franz Ferdinand aren't doing much better. Makes me want to rip their CDs and sell them on eBay; they don't deserve much better.