A very simple way the writing could have even made her full on villain turn more believable is something like this.
Last week, instead of losing Rhaegal, they get shot at with the guns and back off, but Euron still turns on the ships and Dany still loses Missindrei. Dany then has a couple of days of brooding the loss of the Missindrei, then gets rejected by Jon, but she still isn't set completely over the edge. Then during the battle, Dany on Drogon and Jon on Rhaegal lay waste to the weapons just as Dany did with Drogon. They then both sit on the walls on their dragons. The bells ring and then after that, a stray gun (that was missed by Dany/Jon) fires and hits and kills Rhaegal. In that moment, then Dany just snaps and goes on her Mad Queen rampage. It just makes far more sense and also makes the dragon destruction of the weapons far more believable, while also taking out the nonsense of how Rhaegal died, thus fixing two episodes almost simultaneously.
I mean it isn't that difficult to craft far more realistic and believable story lines, they just have two nimwit hacks writing the show and they are wholly ill equipped to craft this story without the books as a guideline.
Eh, that's a little too random chance, Dany's arc feels more earned to me if it's not a straw that breaks the back situation, or even an immediate response to provocation at all. She needed to stew on it and then go for it. And it's hard to sell the Scorpions as a legit threat if they just, like, lightly wound a dragon like we'd already seen them do. The execution of Rhaegal's death was worse than the idea.
Just have her lock eyes with Cersei after the bells ring and go straight for her, ignoring the mass civilian casualties - I was pretty sure that's why they played up having all those people in the Red Keep for "safety" last episode. Then branch out to attacking the Lannister military in the streets, including the ones running with civilians. Wildfire caches go off, etc etc and now the whole city's burning.
CLEGANEBOWL!
That's all that mattered last night! All that hype, and we finally got it. Well worth the wait.
I enjoyed the CleganeBowl but it was pretty jarring because one of my last rewatches was the Hound in the inn where he fights a handful of Lannister men and it's just a knockdown brawl that he needs Arya's help to survive. Skip ahead a few years and he's kicking things off by killing about the same number of what should be Queensguard from low ground while barely needing to move. Leveling up baby!
Who'd've thought a few years ago that Game of Thrones would wind up less realistic than the Star Wars prequels on the benefits of high ground?