Not just that, the Japanese and the Chinese are widely considered two of the more villainous factious. The Clans diluted that somewhat, but between Kuritan expansionism and Liao... existing, it doesn't paint a very good picture. Hell, you could even throw the Clans in as a negative caricature of the Russians and the Mongols.
The setting is absolutely diverse. But it's diverse in a far more organic way than 90% of shit being produced these days, and that's how I want it to remain. If you're not having a setting where everybody is just the same uniform shade of brown (which is what happens when everybody intermixes in a cosmopolitan society), then absolutely you should have different, well-defined cultures and ethnicities vying for dominance because BT is a human setting and that's what humans do.