I think this is likely to be true for every artistic creation that requires lots of capital and widespread human coordination. Ultimately for a TV show to be great many, many things have to go right, and much of what could go wrong happens after the money is spent and the air date is already assured. I'm grateful we've had so many great things, certainly far more than I'll have time to watch in my life. But I'm not a heavy TV viewer.
TV has a fairly bad record of keeping shows that are already shown to be good alive though because good does not equate profitable for the network or individual decision makers (which are again no the same thing).
That's just one of the things that has to go right: marketing, finding the audience, being in the right places and place in time for your target viewers, etc.
I think the problem nowadays is that there are so many channels and so much space to fill. TV runs 24/7 now on hundreds of channels. In many cases, it isn't worth the while of a small channel to make an expensive programme as they would lose money.
Sometimes, the "wrong" programme is the hit. I know the History Channel started off with serious documentaries (some of them excellent quality) which not enough people watched. They then tried Nazis and Ancient Egypt, but it seems to be "Ancient Aliens" which is their biggest hit. Its version of history is questionable, to say the least.
How many people even watch TV "channels" these days? Seems most people have moved to a la carte streaming services. I don't really like either myself and prefer local copies of films but seem to be in a very small minority there.
I've been having a lot of trouble with Amazon Prime. I specifically have it so that I can download films and watch them offline when I don't have internet, and yet the player keeps glitching. I do prefer physical media because at least I'm owning it instead of just hiring it.
Yeah, I don't really consider it a local copy when I can't play it in a player of my choice on any device I want. I'd be fine with digital files (although having a movie shelf is nice) but that isn't really an option so physical media (ripped to a hard disk for convenience) it is.
Well, A-Team was objectively terrible but I have a nostalgic connection to kids shows like that, Knight Rider etc. In retrospect Bay Watch was an effective CPR training tool at unprecedented scale.
Edit: And Star Trek, and Cosmos