The actors thought the dialog George wrote was bad.
I suppose they found the replacement lines by the co writers more satisfactory.
George never wrote Star Wars, Empire or Return of the Jedi without other people writing on the movie.
He mistakenly thought he could write a script without help the first such script since the rough draft screenplay for star wars.
As much as i see the rough draft as an interesting oddity all the flaws and weaknesses in Phantom Menace were already there.