If anything, that was probaby an accident on his part (emulating great films).
This is so true when it comes to art. Artists try to emulate the stuff that has influenced them and somewhere along the way, it takes on a life of its own and becomes special in some way. This is exactly what happened to Star Wars. The unbelieveable part is Lucas trying to backtrack on it with ROTJ. It's like he was deliberately sabotaging his own work by "kiddifying" it or something.
Most artists would DIE to be in Lucas' shoes back in the 70s. They would have loved to create something that unique and special, but Lucas just pisses on it. Really sad actually. After seeing the PT and what he's done to the OT, Star Wars simply represents to me one big missed opportunity. It could have taken its place right up there with Lord Of The Rings as one of the great fictional pieces of all time and Lucas could have been right up there with Tolkien, but that's not the case anymore.
In time, all Lucas will be remembered for is his technical contributions to the film industry and the constant tinkering with Star Wars will eventually negate any achievements he's made as a storyteller.