You do need rape if you want to put Sansa's character through rape though, simple as that. The same way you need to chop off Jaime's hand if you want to have Jaime's character to be without a hand. I mean, it's not that they just want him to miss a hand, it's that they want to cripple him by removing some fundamental part of his being, and they (he really, add this is canon) want his character to grow and change from it. They could use some other plot device to humble him, they could just make him have a few epiphanies here or there either. The process of him having his hand removed changed his dynamic with Brianne and seeing the brutality of it was shocking and a reminder to the audience that even characters we start to appreciate in our own ways can suddenly have things happen to them that surprise us.And you didn't need rape to do any of this. If that's D+D's point, it's still lazy writing.
I mean, think about it: if Sansa hates Theon because she believes he killed her younger brothers, how does her being raped change that? How does rape logically create that bond in a way their mutual hatred of the Bolton's wouldn't have? People are arguing that this makes sense because the show is saying, "this makes sense." But it doesn't make sense.
Also, not all controversy is good controversy. The conversation this episode generated is not the sort that makes people go "Oh, That Game of Thrones show sounds so good! Female rape as an overused plot device, let me check that out!"
Sansa as a character has so far remained relatively unscathed, having her lose her virginity to a monster she married is such a big turning point in her character and her environment. The bond between her and Theon doesn't have to be some cookie cutter "enemy of the enemy" cliche, but can be a different sort of bond. Not even a good or healthy bond, but a profoundly complicated one. How does Sansa look him in the eye now? How does he? How does this change their relationship and dynamic? These are extremely interesting questions we can ask ourselves now, that we couldn't without this plot device. I have seen bonds where two enemies join forces to thwart evil and over time learn to appreciate each other, or some variant of that, but I have never seen something like this happen for. The opportunity this provides the story is very unique and can go in a lot of interesting places.