George Lucas is capable of brilliance as a filmmaker, but in the past two decades has apparently bought his own press and has made some frustratingly questionable decisions that have harmed the quality of his projects.
For instance, in his recent films he has been unwilling to collaborate with a screenwriter who might outshine him; he could afford William Goldman but instead he used Jonathan Hales, who penned some of the Young Indiana Jones TV series episodes. As a result, the recent Star Wars prequels have been saddled with truly awful dialog. Haley Joel Osment tried out for the part of young Anakin; instead Lucas decided looks were more important than any vestige of acting skill and chose Jake Lloyd.
He also has the tendency to try to re-write history in his interviews and director's commentaries when it comes to the original Star Wars trilogy.
To hear him tell it, Harrison Ford was a carpenter he found laboring on a back lot before Star Wars. Star Wars made Ford a star, certainly, but by the time he was cast as Han Solo, Ford had logged speaking parts in six movies (he had been in seven movies before Lucas cast him in American Graffitti). Most any actor would take that as a sign of a career well underway; he was certainly no hammer-wielding rube. Ford was a professional actor who had a rather better-paying backup job than the hordes of other professional actors in Hollywood who wait tables to make rent between acting gigs.
Lucas also portrays Star Wars almost as an indie film, a labor of love and effort by a plucky band of filmmakers who unleashed a Jedi-like surprise attack on the box office. To hear him tell it, nobody had a clue it would do well.
20th Century Fox, Lucas, and other industry folk certainly had an inkling Star Wars was going to be big.
You may recall that Ralph Bakshi's animated fantasy film Wizards was released a bit before Star Wars in 1977. The original title of Bakshi's movie was War Wizards. Lucas felt that the presence of two fantasy films with "War" in their titles would be confusing to the moviegoing public, so he asked Bakshi to change the title of his movie.
In exchange, Lucas offered to open Star Wars a few weeks later than planned, thus giving Wizards a bit more breathing room at the box office (Wizards made a great deal of money its first few weeks, but after Lucas' film opened, theaters started dropping Wizards in favor of Star Wars). Bakshi took him up on the offer; clearly he realized Star Wars was a force to be reckoned with.