Mysterious and spiritual Asians?...An Asian magic negro?
When the movie was made the percentage of Asians in the USA was 1/3 what they are today. People in parts of the USA away from the coasts might not see many Asian people. Today that is not the case.
Myagi seems to be the classic magic negro character in Japanese form with special spiritual powers and insights. He is a 50 year old man who can beat up a whole team of 17 year olds including the toughest kid in town. We never see Myagi train or work out. He just has this mystical ability to kick ass!
Because most Americans had little personal contact with Asians Hollywood can get by depicting them as mysterious and deep. Myagi is more moral and spiritual than any white person could ever be.
Because Myagi comes from that magical minority place he is far from a well rounded person. God forbid he might have sexual desires and want to bang a woman he is too busy meditating and being deep.
Myagi also has healing powers. Remember when he heals Daniel's leg? He slaps his hands together and rubs. Then in deep deep deep meditation none of us white folks could never understand he treats the leg.
It's magic.