Either way Japanese fighters have largely disappointing in the MMA realm. Can't say because no one knows what MMA is there, when they were basically the founders of it, and MMA was big in Japan before it was in the U.S.
No they haven't evolved to compete with high level fighters of today. It isn't because society there doesn't know the sport. They know it as well as any society in the world.
Japanese fighters for the most part just aren't as good as fighters from other parts of the world. Call it physical, mental, or spiritual differences. But they did not progress....unlike the Brazilians. Many BJJ champs and BJJ fighters have turned into well-rounded fighters. Jacre, Maia, Roger Gracie is improving, Bustamante, Werdum....and so on. They did not get stuck in a BJJ mindset. USA wrestlers also didn't get stuck in a one-dimensional Mark Coleman game. Guys like Weidman, Hendricks, Randy, DC, Maynard, Frankie and countless others didn't sit and rely on wrestling.