The sarcasm points out another mechanism in play here: Parents and children used to enjoy the same things a lot more than they do now, at least in terms of television entertainment. Now, what children would enjoy and what parents would enjoy, have comparatively little overlap. I think we can attribute a lot of that to a change in our attitudes and perspectives. Perhaps, thirty or forty years ago, children weren't as often allowed to enjoy things that their parent's wouldn't enjoy. There was surely a lot more boundary-setting by parents, with regard to the entertainment that they'd allow their children to consume.
In the last several decades, more and more often, parents have turned their children over to television, as a babysitter of sorts. They've essentially given children tacit permission to enjoy things separate from what parents would enjoy to watch as well. And once down that road - once they see what there is to enjoy out there, absent parental editing - they have realized what they enjoy more and what they therefore prefer. So perhaps parents would still enjoy what they've always enjoyed, but now children know that they enjoy other stuff so much more.
Remarkably, things have gone in the exact opposite direction with regard to music, where it isn't uncommon, anymore, for a mother and teen daughter to have significant overlap between the playlists on their respective MP3 players.