Your opinion. Lucas stole everything from Kurosawa, that's a fact, he's admitted that in interviews. Star Wars is a samurai movie. Just because of the immense popularity of the Star Wars franchise, does not a great director make. Well known? Ridiculously so, but he's not even close to being in the top 10.
And yes, Star Wars is a remake of Hidden Fortress. When I watched Hidden Fortress I had the Star Wars feeling all over me.
The Leone's spaghetti Westerns are also derived from Kurosawa's work. The Good, The Bad and The Ugly is derived from films like Yojimbo.
Again familiarity and popularity do not make him great.
George Lucas' Star Wars is the single movie that has had the greatest cultural impact, by far.
I also think you are confusing commercial success with greatness. By that logic Michael Bay is a great director.