The music industry requires separate licensing for music past the initial broadcast of a television show. This has caused many series to recieve edited releases or no release at all. The landmark series "WKRP in Cincinnati" was cut to pieces to remove background tracks of music that were deemed to expensive to re-license. The series "Tour of Duty" lost the soundtrack that was part and parcel of the Vietnam era and experience the series portrayed. The musical performances in the currently streaming episodes of "Saturday Night Live" have been cut altogether.
Many of these shows are of historical import to American pop culture. Create a law that "Grandfathers" the original presentation of shows made before the release of series on DVD was common.