Why do Seasons 2 and 3 of Quantum Leap on DVD have songs removed and replaced with alternate music?

They would have to pay the music artist for the rights which could be too costly. All the music on the WKRP DVD was replaced which hurt the artistic value and realism of the show. Also, the Bossom Buddies original show theme Billy Joel's "My Life" is now an awful studio song on the DVD.