And Just couple of added notes....

You bring up a good point. Alot of great directors are also one genere type of directors where they excel. Francis Ford Coppola and George Lucas come to mind. Outside Godfather and Star wars trilogy, one would be hard to find stand out movies that these guys directed.

There are other directors in this category such as Quentin Tarrantin, Martin Scorsese or Tim Burton, but they haven’t influence the popular culture as much as above directors have.