I'm not caught up in the tv show so I haven't seen the scene in question, but I have read the books so I'm at least familiar with the plotline and where it's going to go. And I'm not really sure how I feel about this event, so I'm going to suspend judgment until later. However, I do personally find the rape scene and people's reactions to it to be very interesting.
See, I have a few pet peeves when it comes to fiction, and one of the biggest is something I call "Redshirt Philosophy." Like the name implies, it's the trend of allowing horrible things to happen to side characters but ensuring that the main characters' plot armor stays fastened. You have things like innocent nobodies getting eaten by the monster of the week, bystanders becoming collateral damage, the main bad guy raping/murdering their way through countless people whose names we never learn, but at the end of the day it's okay, because at least the hero rescued their loved one, defeated the villain, and saved the day.
Personally, I find that trend to be very disturbing. Maybe it's because I've always been pretty empathetic for fictional characters, but to my mind, the only difference between the main characters and those walk-ons is plot focus and viewpoint, and the life of the hero and the people they care about really isn't worth more than the lives of those that are killed just to make the bad guy look worse. It always bothered me how in shows like Buffy the Vampire Slayer, you'd have multiple students die every episode and then just get forgotten, whereas if someone the hero cares about is so much as threatened, it's treated like a huge deal. Meanwhile, I'm going, "But what about the families of those kids that got killed at the beginning? What about their friends and loved ones? Don't they matter?" I dunno, it's just really disturbing to me.
I guess that's part of the reason why I like ASoIaF and GoT so much, because while the books and show are downright brutal, they're at least equal-opportunity about it. There's no plot armor, the main characters have just as much chance of dying as the nameless redshirts, and the deaths actually feel like deaths. Hell, even the deaths of Lommy and the butcher's boy ended up having consequences long after the fact, when in most series they would just be forgotten. It makes everyone who isn't a POV character feel like they're treated as actual people instead of just plot devices.
Now, regarding the rape scene, that bit is still in the books, though it happens to a nobody named Jeyne Poole who had barely any lines up until then and did nothing of significance until she was married off to Ramsay Bolton. But no one really raised much of a fuss other than to feel sorry for Jeyne, because Ramsay's a monster and because it was ASoIaF, and that's just what happens if you're unlucky enough to live in Westeros. The only thing that's really different is who it's happening to. It's still a cute girl that we feel sorry for, but instead of it happening to a nobody character, it's happening to one of the mains, someone whose story we've seen in detail and has receive substantial character development. And that's why people are upset. It's not that it happened, it's who it's happening to. If it had been someone nameless or unimportant, I doubt anyone would have really been upset, even though the in-universe situation would have been exactly the same.
I mean, let's face it. Brutal rape is something that so rarely happens to mains. It almost always happens to other, unimportant characters who are really just there for the heroes to feel sorry for and/or to show how evil the villain is. And if one of the main characters does get raped, it's usually part of the backstory and a major driving force in their motivations. And if it does happen partway through the story, it usually happens either to someone already established as being strong enough to survive and rise above it or someone who wasn't all that sympathetic to begin with. But the cute, sympathetic girl with lots of character development? Nope, barely ever happens. So in that sense, you could say that the show managed to out-Martin Martin himself.
Again, I don't know yet how I feel about this scene. Of course I'm not at all approving of an innocent girl being raped by a monster. But at least the show is sticking to it's equal-opportunity standards of bad things happening to everyone. And in regards to what I said earlier about Redshirt Philosophy, I do find the reactions to be...pretty interesting.