I have never watched, have no interest. My impression from afar, that it lacks a moral core, seems borne out by David French's largely positive anticipation of season eight. Yet I had forgotten my own insight from years ago - not the first time that has happened on many subjects. Fantasy writers eventually tell us what they really think is evil. I recall in Piers Anthony's first Xanth novel the playful treatment of demons, and his tweaking of conventional sexual morality. Yet as the series progressed more serious questions started to intrude, almost unbidden. Grundy the Golem wondered if he had a soul; the front edge of a real hell and real oblivion became central in Night Mare. When intelligent thinkers are honest, surprising this happen.
I gave up on the series as repetitive one or two books later, but I understand from others that he drew back from seriousness. Small wonder he moved on to soft pornography next.
Or consider Oscar Wilde - yes, The Picture of Dorian Grey and other Gothic novels qualify as fantasy before fantasy was entirely a genre of its own. He made his career as a flaunter of morality and satirizer of it, but in the end penned some of the most insightful moral pieces of the 20th C and powerfully made his piece with God. Long before his repentance, one can see his deep understanding.
So I am not surprised that "Game of Thrones" could not find an ultimate conflict internally and had to reach outside itself to remind not only its audience but its characters what real evil is like.