the location wasn't central to the plot in the movie, because Oshii just didn't have enough screen time to put all the plot hooks, that are present in the manga, in.
in the original manga Shirow focuses more on the world and global political and economic processes, than on the story. every chapter is pretty much its own story, save for a few plot lines (like the one with the Puppeteer) that go through multiple chapters.
seriously, guys, I don't expect you to drop everything and read the manga, but IMO it's rather pointless to bring up the movie, since it's so different from Shirow's vision. Oshii had to work within strict time constraints of a feature film so he cut everything that wasn't central to the Puppeteer plot. that almost killed the movie, and it certainly would've if done by a lesser director. some scenes just don't make sense without reading the manga first and knowing Shirow's sources of inspiration.