You're acting like there were only two options for the writers:
a. Set up a situation that would logically end in a rape, and then let the rape happen
b. Set up a situation that would logically end in a rape, and then at the last minute not let the rape happen even though it makes no sense, confusing the audience
Nobody is arguing in favor of the second option. It was the writers' decision that Ramsay and Sansa would end up in a bedchamber with him ready to rape her, and if the show was going to avoid depicting a rape, that's a scene they probably would have changed.
I don't think this addresses my question at all, and I'm going to explain why. You can just as easily argue that GRRM could have avoided all the depictions of Dothraki raping women if he wanted to by not having Dany marry Khal Drogo. He could have very easily written a nice little story about life in the Middle Ages (I know it's not technically, of course, but Martin is on record as saying that this is what he was specifically trying to evoke) and ignored the fact that rape was a common occurrence in such brutal times, but he chose not to (indeed, not whitewashing history was important to him), and it gave depth to the story.
So we get to Ramsay and Sansa. The writers didn't have to marry Sansa off to Ramsay, of course... but it definitely helped to move the story along. I get the idea that you think Ramsay raping Sansa was gratuitous, but once they made the decision about the marriage, they made it an inevitability. It would have been toothless and cowardly to pretend that it wasn't happening. And furthermore, his actions toward Sansa are having definite implications now; just two episodes ago even, when Sansa refused Littlefinger's help for putting her in that position.
So the rape served the story.
And it was therefore not only inevitable, but not in the least gratuitous.
Again, if you are drawing a distinction between GRRM brutally depicting rape in the books and Benioff and Weiss doing it on the show, I'd love to understand where that distinction lies. I'm not seeing it.
She didn't need to be raped to establish that she was in a shitty situation. She needed to be raped because Ramsay Bolton is a horrible person, and there's no way he's not going to rape his new bride. It would not have been true to the character to depict it any other way, and it wouldn't have been fair to the audience to just pretend it wasn't happening. Not all liberal SJW criticisms of mass media are unfair but this one really is.
Eh, not really. Especially when book Sansa is in the Vale and learning to be a Lady Littlefinger. This whole divergence from the books pissed me off more than anything the show has done.. well except maybe for the Sand Snakes.
Seriously? I applaud the change more than most that they've made. Sansa's storyline in the Vale was a real snoozer. But it sounds to me that your problem isn't so much that they showed a rape (or "one rape too many" as George put it) on the show, but rather that they changed what you apparently considered to be a riveting and compelling storyline. Which is fair enough, but aim your shots where they belong.