They rushed the "everything she lost" role via silly plotlines and bad millitary decisions just so she could go mad. That's cheap. What made the dragons and all of her might more succeptable to failure in Westeros than what she experienced in Essos? Was it the giant crossbows that she forgot about when "Forgot about the iron fleet"? <---As the producers pointed out.
Instead of getting a personal kill shot on Cersei and the Lannister army, she burns every man, woman, and child, when her whole character arc has been based on being the "Merciful" Conqueror? The same missa missa who chained up her dragons under the mere ssuspicion that it killed a man's child. Westeros took alot from her for sure, but most of it was via bad decisions and her taking heed to leadership that failed her. You could say most of her L's took place in The North if you wanna go that route. Yet half of those folks she listened to, are still alive, while every man, woman, and child who she had no interpersonal beef with, got fried. That's forcing the Mad Queen arc without killing any beloved character's(Ahem!! The Starks!! Tyrion!!)
But even if her heel happening this quickly is justifiable, why didn't she sack KL literally right after they sliced Missandeis head off? How much time did they really need to sack kings landing if their intent was to make it a slaughterfest anyways? They literally supressed the madness for one more epsiode, even though there were no more developing details between last Sunday and this Sunday that would/should/could pushed her to madness this week. They literally had her sit and listen to Tyrion's council this episode just to be like "screw it". You pointed out how she lost everything, but why does she then decide to go mad once she secured a Victory? She finally has her first military victory pretty much since last season when they roasted Tarly/Lannister army.
Why not kill Tyrion right there and then if she already lost her wits and made the decision to burn KL the night they executed Varys? Why keep Tyrion around to keep fumbling the ball and keep getting chance after chance? Why not just end his arc there and then? Kill Tyrion to add intrigue to Sansas plotline towards the end. Hell why not kill Arya to add even more juicyness?
They could at least let her sit the iron throne first to show the differences in ruling, heraldry, tradition, etc, etc, between Essos and Westeros. They didn't even showcase how Westeros and KL would deal with the return of a Targaryen monarch to the throne. Why have her burn hundreds of years of Targaryen lineage to the ground, even though her whole arc was at least partly based on knowing "Who she was" lineage-wise.. I mean, I guess you can say she broke the wheel, but c'mon.
We all knew she was eventually going to have a heel, but to do it im such a unnecessarily rushed, forced and brutal way was cheap.