so you're saying that if the majority of the fanbase were racists they'd still have to cater to them, even if it's wrong?
honestly, sony KNOWS what they're doing (at least as far as casting goes), they wouldn't have cast her if they didn't see potential in her, she is going to be super big next year with the release of divergent and the fault in our stars and she's getting all sorts of award buzz for her independent films, by choosing her they're catering to the general public, who will know her as a big celebrity and the critics, who all adore her for her talent.
the comic book movie world does not revolve around fanboys, because most fanboys are insane and will complain about everything, and at the end of the day, the studio releases the movie it wants to release, whether the comics fans like what they've done with it or not.