I vaguely remember watching a few episodes of Supertrain, and while it certainly wasn't All in the Family in high quality, I didn't think it was all that bad. It certainly was no worse than The Love Boat (and I recall it being billed as "Love Boat on Rails") and look how high in the ratings that really terrible show was. I think DS and the network was just trying to capitalize on a hit premise, the way the networks tried to capitalize on the success of Bewitched with such things as My Favorite Martian and I Dream of Jeannie. In this case, it just didn't take.
Gerard