Why Can't We Be More Like Japan?

Lately liberals are floating this meme around:

Why can't we be more like Japan? Hey, that's something we can all agree on. A few other relevant statistics.

1. Japan is almost completely ethnically homogeneous.
2. Japan allows very little immigration.
3. Japan has a very strong culture that normalizes modes of behavior.
4. Japanese obesity rates are a tenth of those in the US.
5. Drug addiction is rare in Japan.

If the question is Why can't we be more like Japan? then many on the far right will agree. I guarantee you every last one would make the trade of state healthcare for strongly enforced national homogeneity and norms of behavior. Do you think liberals ever notice that their models for social democracy are places with strong national identities? (Or were until so recently.)