I think usually it’s a cash grab since it’s the record companies that make the decision to put out the CDs and what to put on them.

I usually still buy them anyway since, 1) I collect the releases of whatever the band is, 2) the record companies often allow artists insight into what goes on them which saves us the decisions of what should go on our best-of mix tapes we make, and 3) some CD players just do NOT play CDRs.