I’m currently watching again the last season of Game of Thrones, and I was thinking about what you wrote here. In the show, complexity helps with the construction of the episodes. There they only have to choose what to show. But I agree that in written works semplicity is a must, as Italo Calvino, an italian author, teaches.
Game of Thrones has the benefit of being able to write out side plots at D&D’s will. The showrunners are adapting the story, not just regurgitating the text into a script. I’m not sure many will agree but, exposition (sexposition) aside, the show is better, even where it goes past the books.