One of the worst things about the abysmal failure of setting up Daenerys's evil turn is that, retroactively, every single character who believed in her, fought for her, idealized her, worshipped her, is now a total fucking idiot.
I mean, if they're going for the "realistic fantasy" gimmick, that makes some sense: sometimes the people you put your faith in aren't what you believe them to be, but you hang onto that belief because it's too painful to let go. The thing is, staying in the fantasy genre (especially with the whole "army of the dead" gimmick) railroaded most of the characters into the camp of MUH MOTHER OV DARGANZ.
In an actual political intrigue story, this could have been easily solved by making Cersei a credible alternative to Dany, if you can overcome the latter's 3-dragon lead. It wouldn't even be hard to do: just rip (another) page from
I, Claudius (the book, not the show) and make her a capable administrator, the way Livia was. In the book, despite being a horrible (and occasionally horrifying) human being, Livia was really good at managing the day-to-day affairs of the empire. She may have cared nothing for the people and seen the empire itself as a tool for her own ambitions, but it was a tool that needed to be well-maintained to serve her purposes; as a result, she was ironically the most dangerous to the people closest to her, while the vast majority prospered under her leadership. Contrast that with Dany "the dragon is my character sheet" Targaryen, whose principle method of solving problems is setting them on fire.
But they didn't do a political intrigue story. They did a story that started with political intrigue, then got taken over by the creeping supernatural elements, then pulled the plug on all of those in the middle of the 3rd act to head right back to where they started for the climax. No wonder the plot is disjointed and the character arcs are circular: the looming threat that drove so much of the plot for the last seven seasons now never mattered.
Grey Worm and by extension all the Unsullied? Totally mindless killing machines perfectly happy to slaughter innocents and follow Smokey the Bear's worst nightmare despite having been elevated from the cruelest slavery depicted on the show.
In fairness, the Unsullied are one of the most exceptional things ever put to paper in the entirety of the fantasy genre, doubly so for a story with any pretensions of realism. Add to that the fact that George "I don't like good guys and bad guys" Martin made the Masters so cartoonishly evil that I'm actually insulting many of the complex, nuanced cartoon villains by comparing them to the Masters. For me, trying to slot them into any kind of realistic scenario just returns a massive DOES NOT COMPUTE.