I'm actually ok with Arya doing that kill, wasn't story book ending type stuff but I can see her character pulling that ninja shyt off. Now, we can argue that doing all that in 1 episode doesn't feel as rewarding, specially considering the stakes the show built regarding the White Walkers.
This goes back to D&D wanting to wrap this shyt up ASAP for no other reason that they just want to wrap it up. They built impossible stakes for Cercei vs Dany and Humanity vs White Walkers, so much so that the only way to give resolutions to both conflicts quickly was a) strip Dany of all her power by any means possible, which meant destroying Tyrion as "the smart one" on the show and b) get rid of the WW threat in 1 gigantic battle because there wasn't any more time and money for anything else.
But the killing blow to the NK has never been an issue with me
The Sansa shyt had me
"She's like Littlefinger, she knows what telling Tyrion will result in".
Not only was that not conveyed on screen AT ALL (kinda impossible to figure that shyt out unless you are told so by the creators), but you mean to tell Sana is putting all her moves on Jon's claim, who doesn't want to rule, to save and keep the North? When she already doesn't have any military and fukking Dany up might mean giving Cercei the W? And when she hasn't trusted Jon the whole show and hasn't been able to pull his strings any way whatsoever?
It does seem Sansa will end up keeping the North at the very least, probably having HUGE pull in all of Westeros. But betraying Jon's confidence to pull of a move that wont really change anything is

I mean, Dany was going to become mad queen at this point regardless of what Varys and Tyrion thought or tried to do - and much of what drove Dany mad was because of the incompetence those two showed since her arrival on the continent - and that was going to lead to a confrontation with Jon regardless of what Sansa could do about it.
It felt like the nth time D&D were like "welp

" and kept it moving.