The Happy Ending to a story is one of the reasons why we like stories. JRR Tolkien gave the name 'eucatastrophe' to the sudden and unexpected turn of events by which looming disaster is averted, and the happy ending results. The happy ending is so popular and powerful as to count almost as necessary to the definition of a story.
But what counts as a 'happy' ending? In the past it was often marriage - in the sense that a 'comedy' was a play than ended in a marriage - implicitly a going-to-be happy fertile-marriage-until-death. But modern story makers are often - covertly or explicitly - against marriage, especially against Christian marriage. So there are stories which end in just dating having-sex, or dating, or even going-it-alone. And stories which are based on the false psychological assumption that marriage can be open-endedly redefined without loss of narrative power.
Or a heroic story might end in someone 'saving' their society. But most modern Western story-makers hate the society they live in: their stories are indeed dedicated to subverting, destroying or inverting society. So saving, as the climax, is a problem...
One answer is to make-up an acceptable-evil against-which the hero can strive; evil can take a politically-correct form. Indeed, modern storytellers hit several birds with one stone - so the evil people tend to be right wing, racist, sexist, anti-immigration, and actively keen on torturing and murdering as many people as possible... so a story is made about heroic opposition to such people taking-over, or about an heroic taking-over from such people. This was presumably the reason for the vogue of dystopian novels: it was the only possible heroism.
In other words, stories used to be rooted in 'universal' aspirations and motivations; but now we live in a society when the traditional universal aspirations are regarded as extremely evil... so storytelling is necessarily weakened.
The consequence is the anti-story; a story which is supposed-to-be admirable because it overturns the basis of traditional storytelling; by inversions, substitutions, extrapolations etc. An anti-story can't be good as a story in its own right; but only by its being the negation of a real story. The pleasure is therefore political, not narrative.
And therefore people merely pretend to enjoy anti-stories; insofar as they really do enjoy them, they are enjoying them precisely because they are not stories - just as critics enjoyed modernist music or painting because it was not music or painting.
In sum - modern storytelling is oppositions; because modern culture is Leftist hence oppositional. To enjoy it, one has to enjoy opposition t stories; to keep enjoying it, one has to remain in a perpetual state of opposition: piling subversion upon subversion without end.
People ask why the quality of art has declined, why there are no more geniuses? This is one reason - because anti-art has had the highest status over the past century; and one cannot be a genius of anti-art - only a subject for the next wave of subversion.