Creativity, Imagination (and personally Genius) are the main words that can describe them.
I love how Baz Luhrmann can, throught nature, give an emotion and create a story. Just like Terrence Malick, in the "Thin red line" the narrator said: "What's this war in the heart of nature? Why does nature vie with itself? The land contend with the sea? Is there an avenging power in nature? Not one power, but two?"
I did my first movie from my senior year based of how these two directors could express an emotion and a story by filming the nature.
Spielberg, Lucas and Cameron are just the 3 best directors of the century. Of course I speak for myself but they clearly changed, improve and helped the movie industry being revolutionized.
I'm not really into deep dramas. Few independant movies are worth it. And directors saying that special effects destroyed the film industry clearly doesn't get what "CINEMA" means.