I do think making fewer episodes has affected the quality and lifespan of television. As art, the British method of serials over series, except the four or five shows that have been running since the war, is probably superior.
I do enjoy the British's way of producing shorter serials more than the longer American series to be honest, and I find that their condensed storylines means that whatever messages or commentaries they had in mind are more impactful as a result, rather than losing the appeal and spark after 5 or 6 seasons. A lot of Ricky Gervais' series like the UK version of The Office were done like this to great effect, having merely two seasons or less for a single series, inserting their social commentary in this brief period and moving on to seek the next big subject to talk about as society evolves over the years.
I think there's ultimately good and bad to short and long form storytelling, but we are starting to see just how strong of a narrative the shorter ones could produce in their first season. And if writers are struggling to write series that are compelling for more than one season, maybe they should just be that, a single-season narrative before moving on to new experimental projects. It would certainly encourage the breeding of new and novel ideas, I feel.
But seriously, if you are going to write a long form story, at least have some idea how it is going to end. I cannot stress this enough.
I think it's a little more complicated than that. As I mentioned, a showrunner like Chris Carter did have an idea how The X-Files was supposed to end, but the network demanded otherwise because of how successful the series has become. No way they were gonna slaughter the golden goose. I believe most showrunners face this dilemma as well, having a series going beyond their control because of how successful they've become, that even if they wanted to end it sooner than later, the profitability of the show makes it impossible.
@Oromous Depends what you class as a sitcom. If you restrict it to the old style work place, or friends meet up and chat about their lives in a pub or coffee shop type show then that probably is gone (although shows like HIMYM and the Big Bang revived it a little), but if you extend it to modern comedy shows like Brooklyn Nine Nine, What We Did in the Shadows or The Good Place then its still alive. To me the sitcom is a ever changing form. Those are still situation comedies, its just they've changed up the location and experimented a bit more.
I was mostly referring to the former category, yes. But I think what I failed to emphasize about the flaws of the sitcom format is the status quo. For traditional sitcoms like the former group (HIMYM and Big Bang), status quo is god. That's why you'll rarely get meaningful character development that will span over multiple seasons. The Simpsons is perhaps the biggest offender of this, with an episode of season 9 literally reverting the entire history of an iconic character whom I shall not name, revealing that this character audiences have been following had stolen the real person's identity. Even when there is meaningful character development in sitcoms, it happens very gradually, like what happened with Ross/Rachel and Chandler/Monica in Friends.
It's good to know that there might be sitcoms that seek to change this dated format into something better - as all genres really should IMO, constantly evolving and changing - but I think that those who still seek the status quo, they just aren't as appealing anymore, at least to me, when compared to the more realistic and meaningful characterization in TV series nowadays, even comedy series.