I always loved the end theme as a kid–MTM meow and all–and was amused to no end to find this out as an adult via internet search. I was going to post this if you hadn’t.
as to the larger question posed ITT, I can’t speak about home video releases but the syndicated network television re-broadcasts still include the original music. One of the many classic-tv formatted networks I get over-the-air had the WKRP re-runs on for a few years pretty recently. Really was a great show and the music selection was surprisingly good, if not downright excellent at times. Also, I love trainspotting all the promotional posters in the booth and hallway. Some great stuff there, too, and really reminiscent of the atmosphere at my college radio studio in the 90s.