Been robbed before and been threatened with rape and murder while slammed against the wall.
Both were horrifying, but even though I lost three hundred dollars from the robbery, the mere threat of rape and murder and the dehumanizing inherent in that threat was more horrifying and traumatizing than the robbery was. Rape is used so often because it gets such a strong emotional gut reaction out of people, which things like robbery does not.
Is robbery not bad? Of course it is, but it does not get the strong reaction out of people that rape does. When I hear someone got robbed it does not invoke the same reaction in me as hearing someone got raped. One will ****** me off, the other will make me want to kill somebody.
Why specifically rape? Because it is the worst of the worst. Only thing worse would be the same happening to a child, and Bioware even had that being implied in dragon age 2.
It is precisely because rape is so recognizably horrendous that it is such a go to. It never loses it's kick and power, it's that bad.
All the other things occur in games and media as motivators, but they are largely ignored or barely recognized because they lack that same blow to the gut that rape does. If one hundred non rape scenarios occur, the one rape scenario will stand out like a beacon amongst them because the rest are just not as powerful.
It is precisely because rape is dehumanizing and horrifying, right up there with slavery, that I don't think it should be used as often in novels, video games, etc.
When we see rape as the go-to horrific event used against women (but almost never men!), it begins to lose that emotional gut impact that you talk about. In fact, I never, in the scenes I've seen in a game, really gotten the impression I'm supposed to find the victim dehumanized--but I'm often given the impression I'm supposed to feel sorry for the boyfriend/husband/protagonist who's seeing it happen. What this does is detract from actual sympathy and empathy with the victim. And it's easier to do that when it's the go-to Harmful Thing that happens to a character.
Unfortunately, I believe you're wrong about rape scenes losing their impact and power. If they hadn't, then we wouldn't have kids throwing around phrases like "I totally raped that guy," when all they've done is defeated an opponent in a video game. We wouldn't have people JOKING about rape as if it were something hilarious, or grown men I've known saying they totally raped their future wife in a car deal (yes, I knew someone who said that--I didn't like the guy already but after that he COMPLETELY disgusted me). When you saturate the media with something, it loses its impact, at least until it's something that happens/has happened to YOU, specifically, or someone you care about.
A robbery, beating, or attempted murder can also be horribly dehumanizing--particularly if it is a hate crime, and you know it wouldn't happen to you if you were only the "right" race, or the "right" gender identity/sexuality.
I'm not going to argue with you that a robbery, beating, attempted murder, etc. are worse than rape. They aren't. Rape is horribly intimate (and is often even committed by a person you know)--someone knows you don't want it, and they're going to ignore your wishes and force it on you anyway because it's what THEY want. They don't want sex, they want rape. What I am arguing is there are other ways to get the point across that, for instance, elves are horribly oppressed in the Dragon Age universe. It did not need, in any way, shape, or form, to be rape. Beatings, jailing everyone who gathered, killing a few of your family to set an example, burning your home down... any of these things could have happened to an elf, and they'd basically be helpless to stop it. It never needed to be rape.