If you prefer, here is clarification:

"Pornography is sexually explicit material (verbal or pictorial) that is primarily designed to produce sexual arousal in viewers. This definition is better: it deals with the problem of anatomy textbooks and the like. Indeed, this definition is one that is frequently employed (or presupposed) in discussions of pornography and censorship. (See e.g., Williams 1981.) Of course, it is important to distinguish here between sexually explicit material that is wholly or primarily designed to produce sexual arousal (i.e., whose only or overriding aim is to produce sexual arousal) and material whose aim is to do this in order to make some other artistic or political point."

Primarily is key here. A side effect of anything can be that arouses a certain group. This article cites anatomy text books. No publisher got together and said, "I want to find a way to stimulate a bunch of people. I'm going to write a 1000 page textbook about anatomy and leave some naked pictures in it so I can do so."
The primary purpose of anatomy books is to educate on anatomy. The primary purpose of Michaelangelo's David is art, the fact that someone got turned on by him is a side effect.
The primary purpose of GOT is to entertain, (some would argue art and political commentary as well, but that's beside the point). This is not a pornographic film designed to arouse people but set in the middle ages. I assume there are already those in existence. This is a show designed to entertain that happens to arouse some individuals, much less often as the show progressed.