In its heart of hearts, "Star Wars raped my childhood" is still a rape joke. Ironic distance or absurd hyperbole don't make as much of a difference as people think. It's a hifalutin' version of tagging the end of it with "lol, just joking."
Now, if there's some sort of a moral perspective involved, where the joke is really interrogating the way we deal with this stuff and doing it in a humorous way? Where there's actual examination and discovery involved? I'd find that not just acceptable, but also compelling.
Think of the way Louis CK likes to juxtapose our vision of ourselves as moral beings with our baser urges and bad behaviors. (His bit about child molesters from SNL, for example.) Or the way George Carlin examines the way we try to shield ourselves from the terrible things in the world by shrouding it in special language. (His bit about the evolution of the term "shell shock.")
But that takes much harder work than just imitating people's ridiculous behavior in order to mock them. There are comedians who spend countless hours finessing their jokes and dedicate their careers to a laserlike examination of our linguistic foibles, and even then, they sometimes don't stick the landing.
To find humor in a humorous subject, the humor itself needs to be taken seriously, you know what I mean? There is genuine peril in a joke that undercuts the weight of a serious subject, especially if the joke goes memetic. It contributes to a culture that doesn't take that subject seriously enough and sees frequent injustice as a result.
I fully believe there are certain things we shouldn't joke about lightly. That said, I don't subscribe to the idea that there are certain things we shouldn't joke about, period. To me, saying we can't joke about something at all is just a hair away from saying we can't talk about something at all--as if we're ending horrors by simply purging them from our discourse.
As for the Obi-Wan meme, nah. It doesn't deserve an extreme reaction either way. Textbook edgelord humor.
So... anyway... how about those Star Wars? Sure were lots of wars. And stars.