There was a skit on SNL a year or two ago that was a pseudo-documentary about the making of Game of Thrones. There are two creative forces in charge of the show: A man who made sure that the show was accurate to the spirit of the novels, and a 14 year old boy. The 14 year old boy was the one who kept insisting on putting a lot of naked women everywhere.
All HBO shows are like that. Complex, intelligent storytelling and way, way more sex than is actually needed for the story.