Of course they do, that's why we have a definite grammar of shot editing used in the vast majority of movies.
Still not applicable.
The form of cinema was shaped by the men I mentioned, along with many notable others (Hitchcock included!).
With all those notable others--and we can add Leone, Ford, Ozu, Kurosawa, Dreyer, Murnau, Lang, Riefenstahl, De Sica, Kazan, Polanski, Coppola, Kubrick, Spielberg, Cameron, Stone, Tarantino, or the freaking Wachaowskis--any one of them could be removed from the blue prints, and the house of film, as it is in 2013, looks pretty much the same. Because, with all those people, it was ultimately a community effort. Remove Lucas, and it's a completely different style of house.
Never mind the fact you seem so set on limiting your scope to direction. That completely misses the point.
Lucas's impact goes well beyond that of any job title, not "director," "producer," or even "special effects maven." It's simply a matter of his total influence on the medium, as an art form and a business, as an individual.