I agree that a lot has to do with their culture and views on porn.
But of course, as others have pointed out, there are tons of asians in Japanese porn.
I think size also plays some role, as un-PC as that sounds. I just don't think there is as large a percentage of Asian guys out there with 7 plus inches that is almost minimum for American porn. Even the Rick Lee and Hung Lo are only about average size, but small for porn stars. Also very rare to see anything over 6 inches in Japanese porn.
But of course, as others have pointed out, there are tons of asians in Japanese porn.
I think size also plays some role, as un-PC as that sounds. I just don't think there is as large a percentage of Asian guys out there with 7 plus inches that is almost minimum for American porn. Even the Rick Lee and Hung Lo are only about average size, but small for porn stars. Also very rare to see anything over 6 inches in Japanese porn.