I'd thought I would never say a Blizzard character has much better writing then Game of Fucking Thrones, but yeah, Arthas is what Danny should have been if they did her fallen hero arc right.
Oh yeahhh... Well, wasn't Arthas basically pushed toward all that by Malganis and then went insane over Frostmourne?
I can see how Cersei can relate to this storyline by taunting with Dany's mind and pushing her to the brink, but the show runners just wanted to end it all without some kind of momentum so here we are.
I'm guessing it's not as simple as belligerent fans are claiming. I'm sure there was a lot of conflict between the show writers, GRRM, and the actors themselves for how this thing was going to end. We know HBO wanted more out of the show, but GRRM wouldn't want HBO stepping on his toes for his book plot line so there couldn't be any overlap with the A+ version of the story... I bet the actress portraying Dany didn't want her character collapsing into an unlikeable villain a season away from the end... D&D probably didn't want to add a lot of build up that became extremely difficult to write (and fans would probably call it filler), considering GRRM himself can't write his own books anymore. This project is massive and tough.
Am I annoyed we have annoying plot elements like 1-episode Long Night, Aimbot Euron and nerfgun Euron, etc? Yeah. Am I grateful I am seeing the fate of all these characters I started reading about over a decade ago? Yeah. I will rewatch the season after it ends and probably enjoy all of it. Arya killing NK and Euron killing Rhaegal will always bother me but it is what it is. I'll read the books if they ever come out. Let's see.