They have for me - I make copies of many of my CDs and load them up into a set of Sony 555ES changers. Not the utmost in audiophile quality, but not horrible and perfect for hitting "Random" - very much like having your own radio station. It doesn't replace critical listening nor the desire to listen to whole CDs, but sometimes I don't want to do either of those things. I have about 700 CDs in the changers and the list is growing.
One of my favorite music purchase is the Rhino compilations (Best of) CDs of music from decades past. Perfect for filling the changer with. I have probably bought 200 CDs a year the past few years (of all types) - that number will go WAY down if more of this copy-guarding continues to proliferate. -Kirk