I can't see why a unique culture ought to be 'preserved' as people say, either. And I can't see why the 'bad' parts cannot be slowly eroded over time. Nor do I see why certain 'races' ought to be kept. This has always been an argument that's been relatively ignored - why exactly is it desirable to keep a certain race or culture, especially when certain elements of that culture are horrible?
Please do not misinterpret me; I do not speak in terms of some 'white man's burden' in a colonial way. It is ultimately the decision of the Japanese citizens. But I do not see why they should be motivated in the name of nebulous and vague concepts of pride rather than what is best pragmatically.