Ok, I'm probably going to get flamed for this, but I'll say it anyway.
It's a movie.
Dakota Fanning is not ACTUALLY being raped. Other movies have had things like this in them, so this isn't something new to Hollywood. This isn't some "new low". Most of you love those blood pouring gore fests, right? Why are those more socially acceptable? Is it better to be a mass murderer than to rape a child?
I don't know a lot about this movie. It looks like it could be one of those "you can get through it if you try" types. If that's the case, I think the rape scene might be neccesary. There is no better way to convey a message than to show it directly.
So all in all, this is not a horrible thing. This could show people that things like this REALLY HAPPEN in real life. Because as much as you want to lie to yourself, they do. Children are abused. People get raped.
It doesn't change if no one knows it happening.