Basically, I don't think George would have gotten away with making a film like Phantom Menace if it had been the first SW film. Imagine also, if he had made Menace back in 1977 with the same script, a different cast and 1977 effects. I think it would have been the turkey many predicted Star Wars (A New Hope) would be. Could you imagine going into the theatre in 1977 and having a dude in a Jar Jar costume, no pod race, a less impressive lightsaber fight and a very complicated plot dealing with trade disputes, senate meetings and midichlorians?
It's just kind of ironic that many prequel fans not only dislike the OT, but seem to have no respect for the films, especially for the original SW which they find boring, slow and old looking. I wonder how many of them realize that without the OT, the prequels never ever would have been made.