@bolded

Looking back I don't remember her showing any emotion when executing people going right back to Season 1 when her brother died in a most brutal fashion.

She has the ability to switch off all emotion and de-humanize someone if they don't follow her.

Why does the whole town explode when Misses flies her dragon over it and breathes fire on the STONE buildings (less than a second per STONE house)?

Depends on how you define innocent, enemy or traitor. If we look back to Essos for instance, after the siege of Meereen she indiscriminately and randomly picks 160+ of the Masters to be crucified. We justify it because they were slavers and because it's presented as a liberation with the brutality of the slaver children fresh in our minds beforehand. But as we see in later episodes some of the Masters treated their slaves well and would not have been involved in those actions, but to her, it's black and white.

Given her narcissism which has been on display for many seasons now, who she's see's as an enemy is also fluid and especially as her most trusted advisors (who typically calm her more ruthless side) are now dead I really don't see this dark side of her as a particularly rapid turn of events. 

"The more the better"

Thi is the approach the writers took on this one.
You know, like when Michael Bay made the first Transformers movie and thought: 'You know what? People love explosions! yeah, if we put more explosions people will love the movies even more!"

So these writers sat and said:

- "You know what? People love to be shocked. What can we do to shock them even more? I mean, we have already beheaded our seemingly main character. Then we slaughtered our new seemingly main characters while stabbing a pregnant lady in the guts. And then we burned a little girl on the stake. I mean, what could we possibly do that would top that?"

- "Well, we could have Dany attack the Red Carpet, killing in the process hundreds of the civilians taking shelter in there"

-"Nahh.. We NEED MORE"

- "Ok, how about after ringing the bells and the city surrenders, Cersei gives the order to activate the traps with wildfire, killing most of Dany's troops, causing Dany to completely lose it"

-"That sounds cool. But not shocking enough. We NEED MORE"

But it turns out the more is not always better. Just like you, I was totally expecting Dany to snap, but when it happened I was like: "Really? this is the best you came up with?. Sorry but to me the whole scene seemed so cartoonish that I just couldn't stop laughing at it.

Nah man, I don't like or watch Transformer movies and stuff like that. I thought it was good writing that she snapped after the city surrendered. When I watched and the bells rang I was a bit baffled that after her scenes with Jon and Tyrion she would just take the city without killing civilians. She was obviously going crazy and Cercei did not surrender. She did threathen to burn the city down.

What I liked is that when she started killing they didn't show her anymore. Even though I was expecting her to snap it left the viewer as stunned as Jon, Tyrion and even Cercei. They were predicting it but hoping for the best. We don't know what's going on with her and what happens next. 

Your examples might have worked too but it would be a little straightforward. It wasn't supposed to be yet another moral choice for Dany to accept civilian casualties among enemy soldiers, we've been past that. And Cercei with another surprise trap..meh 

Harrenhal wasn't attacked by death lasers. Aegon charged at them from above with his dragon and everything that was flammable within the castle started to burn. The towers started to glow and even partially melted from the heat during the span of a night. Then no one after held it long enough to maintain the castle, which didn't help it too.

Even GRRM, the man who apparently thinks stew pots can melt gold, was sensible enough not to give dragonbreath the thrust of a rocket engine. The CGI was done for a pretty, but dumb spectacle, worthy of Michael Bay, and that was it.

Ehh... but the bells were supposed to mean that they had surrendered.. And there is absolutely no way she could have known if Cersei had surrendered herself or not because she was not able to see her from where she was standing.

So is not like she thought: "Ok, the bells rang. But I don't know if Cersei surrendered or not. So let me kill these kids on the streets in the meantime"

They were people people living their lives. Again, it's a matter of perspective and we only ever see hers, and as an audience are far more sympathetic because slavery is so abhorrent in the 21st Century, but this is a time and land where slaves are the norm. She's imposing her will and rapidly casting judgement. And as I said a few posts up, when she passes judgement, she loses all empathy for that person. She never displays guilt or remorse, even when she tells Sam about his family.

Her freeing the slaves and unsullied also comes from two aspects of her personality. The first is genuine empathy having effectively been a slave herself in the first season. But the second is that it feeds her narcissism. She is their savior. She doesn't get that in Westeros. In fact, she has a propaganda war raged against her and even after the pivotal role she played in the battle with the Night King, she's still seen as the foreigner. With the loss of her allies and closest friends and advisors, she no longer has anyone to feed the narcissist in her and snaps.

I mean the episode 4 where Cercei didn't surrender but instead killed Missandei. Dany gave Cercei a chance to surrender or she'll burn down everything.

Dany's story was always going to end like this, and there's enough pieces of it here to see why. I understand the frustration, because ultimately that switch is flipped really abruptly, and it feels jarring. If you really think about it though, it's hard to argue it doesn't make sense, even if one might have preferred a smoother transition, where the viewer is really handheld down her path to madness.

Here's this person who's accomplished all these amazing feats. She went from being little more than a slave, and a whore, to becoming a queen. Going from land to land, city to city, conquering everything in her way. Throughout, she was actually consistently ruthless, and demonstrated kindness/mercy only when she knew there was something to be gained by it (not saying that this didn't happen often, but it was always very much calculated). Especially early on, without the benefit of fully grown dragons, these traits were tools she knew - and was often reminded by those counseling her - she required to build a loyal army. The more power she acquired throughout the show, the more she relied on shows of strength. She still had her ideals of course, and sought to be just in her way, but one definitely got the clear impression that her morals weren't ever going to get in the way of her ambition.

By the time she finally arrives in Westeros, she's become very much impatient. All along the journey she was told she had to do this, that, or the other to prepare for this moment, and then she finally gets here, and it's still not enough. So once again, at the behest of those advising her, she devotes her attention/resources to something else. She helps the North defend the lands against this seemingly all consuming threat of the whitewalkers. In the process, she loses a dragon, as well as one of her most longstanding advisors. That's tough in and of itself. This time however, where she previously found admiration, and loyalty from those she aided, she finds mostly indifference, and actually even contempt. They don't look at her as a savior, but rather….the next problem in their lives. Ungrateful. To make matters worse, the man she'd found love with, is discovered to be her nephew, and the rightful heir to the Iron Throne. At this point, her whole quest, her whole life's mission is basically unravelling before her. Even if/when she wins, there's going to be a challenge to her rule. Whether John wants it or not, he's a symbol to the people of an alternative choice. A familiar choice. Not some foreigner who showed up riding on dragons, and huge armies in tow, but a man of the people. The only peaceful way forward, a marital union, is rejected by him. On top of all this - as if it weren't enough - her actual best (possibly, only real) friend, who's been with her from almost the very beginning, is beheaded in front of her.

So, to say the least, her path to "victory" in Westeros has not been kind. In fact, it's pretty much been a disaster. Plans are coming undone pretty much every episodes, she's down to only one dragon, and she's losing basically everyone she cares about in one way or another. Fast-forward to her hearing the bells of surrender. She's sitting there, on her dragon, taking it all in. Has she really won….? Cersei is surrendering, sure….but what did she win? Taking this city, this throne, has cost her literally everything but the dragon she's sitting on. In this moment, she's emotionally broken. Why should it be so easy for these people? They don't care what she's sacrificed to get here. The efforts she made to keep them safe from an army of zombies. That she's deposing a tyrant. The times she took everyone's advice to seek a peaceful surrender, only to be met with more heartbreak as a result. Why should she just be another in a long line of figureheads who's replacement these people await with indifference? This place is broken. It's not worth saving. It's people aren't worth saving. Cersei is as much a product of them, as they, and their situation are of her. So burn it. Burn it all down. "Break the wheel," if you will.

You can argue with the execution, but I think it works. I'm not saying the slow descent into madness that a lot of people wanted to see wouldn't work, or wouldn't be interesting. I'll even accept that it might have been a smarter move on the part of the writers, to lead people down that road bit by bit, and really spell it out. Make it as on the nose as possible, so people don't feel betrayed when a character they love, and have spent so much time with, is at some moment completely unrecognizable in their actions. Reality though, is that sometimes people just snap, and they do so even at moments that make very little sense to people from the outside. Dany certainly has experienced enough to justify such a snap, and all the character traits that would make her capable of killing countless people, innocents or not, were always there. Whether they were usually held in check by her better judgement, advisors, or an eye ahead to long-term benefits, is frankly irrelevant. She hit a breaking point, and having watched her journey throughout all these years, I personally found it pretty believable.

I do agree that it would have come across better if they'd reversed the order in terms of her destruction of the city and the actual keep, but I can live with it. Flying over it anyway so....might as well torch it on the way, right? lol