In the past 10 episodes of so, the show has killed off Stannis, his wife and daughter, Barristan Selmy, Doran Martell, Myrcella, Roose Bolton and his wife and child, Alliser Thorne, Hodor, Osha, and two direwolves, all of whom are still alive in the books. I consider several of these to be important characters - particularly Stannis. So your complaint about the show not killing enough characters just doesn't wash.
I'm fine that none of the principal "good guys" have been offed recently. That worked well early in the books for the reason you described - GRRM's misdirection as to whom were the important characters. But that model isn't sustainable now that we're approaching the final act. The final act will sort out the remainder of the main characters - we're just building to it.
I expect the remaining books will follow suit. You really think GRRM is not resurrecting Jon Snow? Please. Moreover, much of what we're seeing this season seems to be a logical extension of where the books are headed. It makes sense that Jon is marching on Winterfell. It makes sense that Ramsay has murdered his family and seized control.
This show has made mistakes. The biggest was the deviation they took with Jamie's character, reconciling him with Cersei. Thankfully he's now back in the Riverlands where he belongs. But it's still the best show on TV. It's going to bring home 20+ Emmys this year. And it has made a number of significant improvements over the books by tightening certain storylines. For example, Sansa and Littlefinger in the Vale.