The AMPAS not awarding Akira Kurosawa at least one Best Director award is, frankly, a crock. He may not be a household name, but that doesn't mean his contributions to cinema are any less important. Ask any director or aspiring filmmaker about him and they'll start gushing before imploring you to watch Seven Samurai and Rashomon immediately.
Kurosawa's stories about war, love, and life went on to inspire great directors like Steven Spielberg and Martin Scorsese. How does the AMPAS honor the man who inspired today's greatest cinema? They don't. Sure, they gave him a lifetime achievement award, but the Best Director trophy is what he most deserved.