D&D said they chose Arya to kill the night king to subvert expectations. I imagine Jon will have a much bigger role in the book, if we do ever get it.
That's interesting because the showrunners for the Rings of Power have also flagged that reason for their treatment of Sauron in the show (and other choices, i'd assume) - “We were concerned about a situation where the part of the audience steeped in lore is six or seven episodes ahead of the characters. If deception is an important part of the journey, we wanted to preserve that experience for book readers too."
That is a very precarious path to take, for me 'story' trumps everything and if 'forced' subterfuge hurts the story, then it's a wrong choice. I also think it shows a lack of understanding of fandom - fans of a show may well know what's coming if faithful to the book but that doesn't make it any less riveting. In fact it can do the opposite as fans "can't wait" to see THAT scene, they wait with bated breath to see [insert iconic moment here] on screen. Those familiar with animation star wars: if they did a movie covering Rebels you know what everyone can't wait to see - Ahsoka vs Vader, imagine they decide against that cos everyone knows it's coming.... just dumb. There are tons of examples we could all rattle off and let's just say the obvious one for this thread - Red Wedding
It's also a very odd stance as the main reason studios produce well known and loved IPs is because it gaurantees you a lot of chatter, an audience and following before a single episode is aired. To then piss off that audience by butchering a story because you dont want them to know what's coming is kind of brain dead. Of course changes are always going to be needed in adaptations of books but that's usually more of what you leave out/rework while still telling the same story in a compelling way - eg Jackson's LOTR trilogy.
With GOT it was somewhat different in that there was no 'finale' book to go by but subterfuge for the sake of it and allowing the story to suffer for it is kind of a rookie mistake. It demonstrates more a lack of creativity in not being able to tell a compelling story given that the route to the end has been flagged, in this case via prophecy. And even if the choice is the prophecy wasn't infallible and something else takes place, you can't just pull a plum out of your arse, again, it needs to be crafted well.