Lucas is a good director and producer, a BAD writer, a fabulous businessman, and a complete asshole (oddly enough something that is basically required to survive in the film/entertainment industry).

His major contribution to film can really be boiled down to his refusal to except "That is the best we can do."

ILM and everything else sprung from the fact that he would not accept the established wisdom that what he wanted to appear on screen could not be done, he simple demanded that the people he had gathered figure out how to do it, and the people he gathered were VERY good.

He deserves his place in cinema history, but it is not at the top.