I don't think that this is confined to just American vs. Japanese styles. I think that in general the baseball in the 2 regions, (the Americas and the Far East) is more a product of the people and their societies. I'm probably gonna catch it for saying this.
The Americas (US, Mexico, Cuba, Dominican, PR, Etc.) have more bigger, stronger, athletic players playing baseball. We like thinks big. Over here, we're impressed and obsessed with big things like HR's, K's, and radar guns. So our game lends itself to our players and our society.
The Far East generally has somewhat smaller and overall faster players. They have an extreme work ethic and attention to detail imbedded in their culture that the people really appreciate, and probably expect from their players in all sports, not just baseball. So, again, their game lends itself to their players and their culture.
I think that our baseball is a better blend of both styles (AL vs. NL) than it is given credit for, its just that steroids era of the last decade or so has clouded it over. But steroidball is pretty much behind us, and make no mistake, for those who watched a lot of MLB, last season was the best baseball in a long time. Whether you like them or not, (sorry O's fan here) the TB Rays were so much fun to watch with their blend of speed, power, athleticism, and fundamental baseball. I found it funny that everyone kept talking about manager Maddon as thinking "out of the box", when I kept thinking he's playing the game that we're all playing at all the levels below! 1st to third, sac. flies, steal a base, bunt them over, hit to the right side. I'm sure this will continue this season and spread throughout MLB in the seasons to come.
BTW-I'm not sure what exactly a purist is, but before the past decade of steroidball the all-time home run, as well as the other major offensive categories, and strikeout lists were dominated by players that were in their prime in the 30's, 40's, 50's, & 60's. Our memories are often biased by how we wish that our memories were. Another visit to the HOF (one of the greatest places on earth!) will always help to clear those clouds and put these memories back in their proper perspective.