Took a while for this to make it here.
I wanna discuss a few of the more common talking points...
BAD THINGS HAPPEN ALL THE TIME IN GAME OF THRONES, WHAT MADE THIS WORSE?
A question made even more pointed by the fact Jeyne Poole actually suffered far worse at the hands of Ramsay, who has been slightly toned down in his TV characterization (more clown than monster half the time). This is a show where babies are ripped from their mother's arms, Dads are beheaded, and Theon gets his penis flayed. Why is Sansa's rape at the hands of Ramsay so particularly galling in light of this?
Bad writing is a primary culprit. Sansa shouldn't even be there. The justifications for her being there are paper thin and make absolutely no sense. This kind of sloppy, shitty writing typifies the show's deviations from canon. And the last thing you want to be engaging in when exploring controversial subjects such as rape is sloppy, shitty writing. Shows have touched on the subject before. The Sopranos had an extremely upsetting rape episode that was more acclaimed than controversial, because it was a well written show and the subject was addressed with sophistication and nuance. These are two words that should never be associated with GoT's fan fiction. Exhibit A, the absolutely ludicrous and unintentionally comical visit to Dorne by Jaime and Bronn. This is the show the showrunners are crafting for you. It's one small step above the Mighty Morphin' Power Rangers.
So why is Sansa being there such shitty writing?
1. It makes no sense for Littlefinger to leave her there.
2. It makes no sense for the Boltons to basically openly rebel against the crown. Yes, Tywin is dead. The Lannister/Tyrell agreement is still in effect, and the northern armies are still devastated. Roose openly states he has a smaller army than STANNIS at this point (which isn't true, but whatever). Why does he do this?
3. It makes no sense for Sansa to agree to it. What does she hope to accomplish?
4. It stalls/regresses Sansa's arc...she'd been slowly coming out of victimhood and gets popped back in, even more violently. Just because the story is an exercise in trope subversion doesn't mean you can start throwing arcs out the window.
It reads/watches as an utterly contrived situation meant for shock/emotional impact. And when you use rape as tool for shock/emotional manipulation...in a situation where it makes no narrative sense...you are going to come under fire. They actually have a pretty storied history with this too.
1. Jaime and Cersei. Deviated from the books to make a consensual scene look non-consensual. Why? For what narrative purpose?
2. Meera's near-molestation North of the Wall. Never happened in the books. Why? For what purpose?
3. The entire character of Ros and her sexualized murder by Joffrey. Never happened/existed in the books. Why? What purpose?
4. Gilly's near rape in the most recent episode. Never happened in the books. Why? What purpose?
5. If we can deviate slightly from rape and just keep on "violence against women", the clown show that was "Talissa" culminated in a pregnant woman getting stabbed repeatedly in her womb. Why? What purpose?
The books themselves are thick with rape and violence...the show has actually dialed down the latter and significantly boosted the former. Benioff and Weiss see fit to ram a bunch of characters into rapey situations that never existed in the books. The only part where one could make an argument in favor of it was Dany/Drogo in season one, because with all due respect to Mr. Martin her enjoying that was patently ludicrous.
TLDR, discussing or showing rape is not intrinsically bad, but if the way you portray it feels cheap, or exploitative, or poorly thought out and written, it's going to come under serious fire.
WAS THIS EVEN RAPE? THEY'RE MARRIED!
Legally? In Westeros? No. Morally? Most certainly. The show went to great lengths to make it seem as non-consensual as possible. It's a faintly ridiculous defense/debate, frankly.
SANSA *HAS* TO BE RAPED IN ORDER TO AVOID RUINING RAMSAY AND THEON, TOO
That one is my contribution. Putting Sansa in that situation, as absolutely fucking ridiculous as it is, and NOT having Ramsay horribly victimize her would be a violation of Ramsay's character. Of course he would victimize her. He's Ramsay. Ramsay "I name my dogs after the women I hunt, kill and flay" Snow. There are major outcomes in the books that require a certain sequence of events to occur at Winterfell. You start fucking around in order to give Sansa a girl power moment, and suddenly your entire extended plot starts coming down like a house of cards.
Which is why it was absolute madness to even have her there in the first place, and why D&D and the writers for GoT deserve every ounce of shit they've been taking over this, and then some. If you think this season has been bad, you just wait until these idiots are out in the wilderness on their own with only a rough plot outline to draw on. GoT is in the midst of one of the most startlingly rapid quality declines of any show in the modern era, and it's only getting started.