Actually there is some legitimate debate as to whether or not the clean up by Lowry is specifically to blame for some of those losses, like the star fields. But it is a fact that the masters used for the 2004/2011 releases (and Harmy's DeEd) have those problems, whatever the cause. And it sucks that it wasn't caught and corrected (or recalled). So much for supposed "professionals."
Still, since that's the way that Lucas released his Special Editions on DVD and Blu Ray, it's reasonable to assume that that's the way the unaltered trilogy also would have looked, if he had listened to his fans and released it with a modern remaster alongside the others.
"Please leave the remixing to the non professionals George." - this statement is how the reviewer ends his review of the Star Wars Saga Blu Ray boxed set on wired.com