To me, the last season has been all about convenience and that's why it's sucked so bad. I mean convience for the writers. They had the admittedly difficult mission of wrapping up and containing 7 seasons of build-up in only 6 episodes, and they had to do this without the foundation of the books to carry the script which made it poor in comparison and left the dialogue hollow. Without the help of the books the people behind the show showed themselves for what they are: by Hollywood standards middlingly talented writers who've been molded into simply driving plots forward. That's all they know how to do and that's all they did.
None of the crucial scenes (and there were so many, way too many) had any semblance of being important because the characters motivations were entirely hidden from us as viewers and everything seemed just inane. For example, if they wanted us to believe Daenerys was actually rampant and psychotic, then show her BEING that instead of just pressing a button to make her go berserk and then claiming: "Well, it actually makes sense for her to do that in the great scheme of things". It doesn't make any sense if you don't let the viewers in on what the the hell is going on, that's where they made the biggest mistake in my view. They just economised the whole show so much that actual story telling was swapped for montages.
Instead of basing the last season on what made the show decent to begin with – the credible, cynical and neverending politics which always lead to misery – they just laced the last season of the show with fateful music and slow zoom-ins; in essence we were not really told anything that could be a continuation of everything we had learned before, instead characters now quickly acted only in accordance with this concocted and simplistic ending.