Just to add to this interesting discussion; the privileging of male perspectives in story, in film and television, is definitely evident from data, in terms of roles for women in front of and behind the camera:
https://womenintvfilm.sdsu.edu/wp-content/uploads/2020/01/2019_Its_a_Mans_Celluloid_World_Report_REV.pdf
https://www.yahoo.com/entertainment/family-films-twice-many-male-female-characters-says-new-study-exclusive-193648252.html
https://seejane.org/wp-content/uploads/key-findings-gender-disparity-family-films-2013.pdf
And it’s true, sometimes female fanbases are actively disliked and discouraged:
https://io9.gizmodo.com/paul-dini-superhero-cartoon-execs-dont-want-largely-f-1483758317
I don’t think we can analyse all these texts as suffering from exactly the same failings in terms of their ending, however.
Game of Thrones may have tried to surprise fans, but Supernatural and Rise of Skywalker tried to please certain segments of the fan audience (at the expense of others). A Reylo ending for Rise of Skywalker and a Just-the-Brothers ending for Supernatural were fanservice. And it was that, cartoonish idea of, fanservice which impacted narrative and character growth.
Avengers: Endgame - the privileging of the heteronormative family remains a given in products this huge. The ending wasn’t “leftfield” to evade fans who had guessed ahead. The ending was, predictably, normative. Women are seen as a “reward” for male heroism; Peggy becomes Cap’s reward. Women who are not family-normative are seen as expendable; hence Nat’s sacrifice for Barton (because Barton had a heteronormative family). Elements capable of “queer readings” (the team as “found family”, the close relationship between Cap and Bucky) got shut down by a heteronormative ending - dull and regressive, yes, but not leftfield.
In fact, it’s not the narrative trying to “surprise” fans which unites the endings of Game of Thrones, Rise of Skywalker, Avengers: Endgame and Supernatural; it’s the unimaginative straightjacket of (white) heteronormative patriarchy. Disruptive elements allowed space in the middle of the story are given normative endings.
Rey, is the hero of the new Disney Star Wars trilogy, and hey, that’s cool, a woman in the Luke role. But, she’s written by men (and the virgin/ whore dichotomy is, apparently, still going strong with them) and so she is girlish and un-sexual (virgin category) and her story evolves to revolve around a troubled white man (Kylo Ren). Rey’s “purity” saves petulant Alt-right manchild Kylo, changing him back into “nice” Ben. It’s Beauty and the Beast, in space.
Wonderful female characters who were allowed to breathe and evolve over the course of Game of Thrones get put back in their boxes at the end. Cersei becomes just the bitch her “nice” brother couldn’t escape from. Dany becomes just the power-mad bitch her “nice” lover Jon Snow had to murder. And the final scene is Brann’s council (all dudes except Brienne) discussing the need to rebuild the city’s brothels as a top priority. Proper patriarchy is restored…
Supernatural, well, what even was that fuckery. But there are no women, no POC, and no queer folk visible in that final Heaven, only white men-folk. All the interesting elements allowed to breath in the middle of the story were bleached out at the end; blood family was reinscribed as more important than found family; Sam got some blurry heterosexuality; Dean and Cas were not allowed to reunite, in case queerness “tainted” the final bow on the corporate product.
Greater diversity in writers rooms, directors’ chairs, producer roles and, crucially, at senior corporate levels in the film and television business is so, desperately, desperately, needed, to lift the curse of the Boring Dudebro Ending.