I recall reading somewhere that when nostalgia channels began showing the original Murphy Brown, it suffered from poor ratings as well, compared to other classic and vintage shows. People don’t seem to be keen on Murphy and her abrasive tone accompanied with the liberal Dem talking points of even that time.
I was a big fan of Murphy Brown at the time but it doesnt hold up well. The bulk of the humor is anti-Reaganism snark which makes Murphy look stupid given all the 80s nostalgia. The stories are typical leftist style of the time but are now hypocritical - free speech, fighting government oppression all things leftists (and even Murphy herself now, from what Ive heard because I could only stomach about 5 minutes of the new series) now happily support. Its all vacuous.
Surprisingly MASH, even with its leftist bends, seems to stay pertinent by staying on the bigger goals that are still pertinent (war is hell)
That was probably partly due to the topical nature of the show. Old viewers might have enjoyed re-watching it, but younger viewers would not have understood many of the references (political figures, other then-living newspeople, etc).