Is Kusanagi a traditionally oppressed and marginalised Other from a racially ghettoised and largely impoverished urban environment who can be seen to represent the changing pop-cultural depictions of her community as empowered actors? Or is she just a Japanese person living in Japan?
Well, if you think being part of a marginalized culture is really the only important thing about Luke Cage being black that defines him differently from some other character. My argument is that the cultural aspect still applies whatever the race in question. There is no "neutral" or "default" human being outside of the cultural context that gives rise to that person. None of us exists in a vaccuum, we are part of the history and life experiences that made us who we are up to this point in time -- including the stuff we never even think about, or may be effectively blind to, because we can't see ourselves from outside, from another perspective. Although the foregoing is obviously changing in the time in which Kusanagi lives, the world is still far away from being all Ghosts with interchangeable Shells. Maybe in a further future extension of the same sf timeline, there IS no local culture, no nationality, no ethnicity of any kind - only global/cyber culture, a great leveling homogenization where the only distinct subcultures or groups are the ones people choose for themselves.
They're already building some human-looking robots in Japan. Interestingly, Japan seems to be the only culture where there exists a great desire to prove this can be done. Since they're not real biological creatures, they could choose to build one in any image they wish. How many humanoid robots do you think they're building in Japan that have human features that look like some other ethnicity than Japanese? In the few convincing instances of this I've seen, the robots do look like Japanese people. No great surprise there.
I could almost accept this if it were something established in the manga and anime as part of the cultural background of that future -- if cyber-bodies were like suits of clothes, where fashions come and go, and when swapping out bodies, one might commonly choose to "wear the clothes" of another culture/ethnicity than one's own, to graft that image onto oneself as part of one's outward avatar that interacts with others in the physical world - no differently than someone might get a tattoo or decide to dye their hair blue. "The Scarlett Johannson look is in this season." It would seem incongruous to Kusanagi's character and occupation as established in the stories, though. It's the future, but there's nothing here indicating that people in this future Japan don't still think and act Japanese. It's simply a cultural baseline for them.
The movie was being made for international audiences most of whose consumers aren't Japanese, and they wanted a star with drawing power, so the role goes to a Caucasian female, rather than an actress of similar popularity (not sure if there is one) who is Asian and might therefore convincingly play the part of someone who was born and grew up in Japan (or who has a cyber-body made in Japan to be an avatar for a Japanese person, interacting with other Japanese people in the physical world, the locale of which is still a future Japan). All right then, if you're "localizing" the original work for a different culture, then just keep the core sf ideas and chuck out anything specific to the country of origin, changing "Go Mifune" into "Speed Racer". But that lessens Ghost in the Shell
for me and makes it into a much more generic cyberpunk story, and changes the character of Kusanagi into a "generic sexy female action hero" cyborg role that can be doled out to whoever fits that description in the current vogue of movieland.