All about the price point. I pirate tv shows yet I still have a Netflix account and I can't remember the last time I pirated a game since the advent of steam sales. They either need to have MUST HAVE content, which they admittedly might have, or they need to use a price point where paying the subscription cost per month is competitive with the hassle and risk of pirating.
I have competition for my free time, this ain't the 70's with 4 channels. Game of Thrones is indeed a very good show. But I'm not paying a ridiculous sum per month for it. I'll just go spend time with my son/wife, or play more video games, do shit around the house that I've put off, I have no shortage of things to do.
You may call it rationalizing, but I think it's really just some content providers finally realizing that they aren't competing against other TV shows or channels, but against everything else someone can do in their free time.