In their defense, GRRM writes his female characters wonderfully, and the…
And it takes place in a sexist world. Welcome to medieval times. It’s a sad truth, but there it is. You can’t apply modern-day principles to a story that takes place hundreds of years ago.
As a side note, I think Arya, Catelyn, Margaery, and Daenerys do a fantastic job at breaking any stereotypical female clichés. I see nothing sexist in their writing.
Cersei Lannister herself is the entire reason that the game of thrones began and is what it is now. If she hadn’t ordered the death of Ned Stark, we wouldn’t even have a story. She’s power hungry and knows exactly what she has to do to win.
One more thing I forgot to mention: If you’d like more in-depth explanation of the sexism and use of the male gaze in the TV show’s writing and direction, I highly recommend checking out the podcast Fat Pink Cast. They analyze the show episode by episode and don’t shy away from discussing its more problematic aspects.