Game of Thrones was nearly "destroyed" by pirates illegally streaming HBO content
(www.forevergeek.com)
I do think that sums it up pretty well, and as other have said, the last season had a "I don't want to do this anymore, lets wrap this up vibe" and to make matters worse, they completely abandoned so many plots that you thought had a point to them. To me it felt so obvious that during the fall of kings landing, Cersi should have flipped out and Jamie should have killed her. History repeating itself. Maybe that was just too predictable for them to actually do it, but all the character development up to that point was the perfect setup for it and they just dropped it altogether.