Well, it was a Japanese-made film. From what I've seen in other Japanese productions, there aren't a lot of ethnically European people in the Japanese film industry who can actually act worth a damn.
I think the difference is that America has a richly diverse population that the film industry hasn't yet learned to represent proportionately, whereas Japan, until recently, has been a country with very little ethnic diversity in its population, and thus even when it does represent the population proportionately, it's still pretty uniform. So it's easier for an American film to have an all-Asian cast if its creators are willing (e.g. the live-action Mulan remake) than it is for a Japanese film to have an all-European cast.
I have said it before, I will say it again.
Asia is a continent.
Does no one remember the outcry over Memoirs of a Geisha?
I love Lucy Liu and her tendency to walk around with her knees on show in winter as much as the next man, but she probably shouldn’t be cast as the Major.
Regardless. The GiTs Movie did better than that. It cast people from all over.
The most high profile Japanese American actor I can think of is George Takei, and he would look silly in the thermoptic camoflage.
I haven’t seen Pacific Rim, but Rinko isn’t exactly A list megastar.
The film is SF. It appears to be set in HK, renamed NewPort. (At least partially) which is an interesting bit of world building, mirroring the Oshii film a tad.
It’s diverse cast makes it more interesting when you take into account Japan’s population problems, and the world it is showing.
This is also true of the the themes in the movie, and the questions about which identity is real for the Major. Which make it all work, and work particularly well as a comment on the homogenisation of the world accelerated by technology.