But if we expect every novel, play, film, etc. to be a PSA for Good Behavior, we lose access to the part of art that is most connected to our humanity. That is to say: the part where we witness our flaws, our savage desires, our troubling predilections, our shame and longing, selfishness and hope. The parts where we are creatures in flux, caught between contradictions. The parts where, presented with what makes us uncomfortable, we encounter ourselves and each other newly in the discomfort.
Part of wanting every story to be morally instructive is a complete rejection of ambiguity. Not only in the sense of a clear distinction between "Good" and "Evil" but also in the sense that there is no room for interpretation on the events of the story or the feelings of the characters. Or anything else.
In this style of mainstream, institutionalized art that the article refers to, everything must be over-explained. Characters have internal monologues explaining their very linear reasoning for each decision (sometimes with "getting a good grade in therapy" wording, for extra points). In speculative fiction, magic has a "system" and the history of the made-up galaxy is two steps removed from being a wikipedia article.
Cultural institutions don't like ambiguity in the art they prop up because it leaves room for interpretation. It leaves room for a morally incorrect interpretation, which would taint their image forever.
The same people that insist this or that story is "problematic" because the characters didn't spell out the moral lesson are the ones that recoil at open endings. And when they encounter one, they will attempt to "solve" it, explain what "really" happened in that gap left by the author.
And yet.
When I think about the stories and the art that stays with me for longer... it's the ones with ambiguity. It's the stories where a smile could have been a show of teeth and the author won't tell me which one. It's when something unexplained happens and the characters are left wondering because I'm left wondering with them. It's the open endings that I keep going back to, not as an attempt to solve them, but because I keep finding new ways to look at them.
Perfectly straightforward art does not leave much room to put yourself, your perspective, your anxieties and your desires in the story, see how they mix. Ambiguous stories are the ones that have entire scholarly traditions arguing over centuries about what they mean, what they could mean, what new things can come out of them by looking from a different angle.
Ambiguity invites the audience to participate actively. It rewards you for revisiting art and see how it changes based on how you changed. It moves you to share with others, what do they see, how do they approach this?
That's how art becomes immortal. Because it keeps being revisited. But it's only worth revisiting if each visit shows you something new.