I have to go along with what both Wade & Bernd is saying. Firstly, a lot of politics are involved in big budget films. Secondly, Manga generally follow an ‘ideal look’, where among other things, the eyes are more huge, more open, more like baby’s eyes, as opposed to how asian eyes tend to look (and please, I’m not generalising here). Thus you get a more ‘gaijin’ or foreign look. Take a look at how Kusanagi is portrayed in the original manga:
And in the anime:
You could argue that Johansson may not look the part, but apart from her character, by ‘standard’ measures (if you wish), manga in general favours an ‘unnatural’ look if you compare it to the looks of the asian population.