It's been reported previously that when Lucas went back to the original negatives of the Star Wars films in the mid 1990s, they were found to be in bad shape. Such bad shape, in fact, that had they not been restored immediately, the films could have been lost forever. So restoration is exactly what Lucas had done. Except that when he was creating the new 1997 Special Edition versions of the films... he cut the original negatives. So the original negatives of the theatrical versions no longer exist. Okay, we knew that. But what's the big deal? What about the original interpositive prints? What about high-quality release prints? Why can't Lucasfilm just use either of those elements to do a new transfer for DVD?
Well... at the same time as he was preparing the 1997 versions, Lucas apparently went on a little tear and recalled every release print of the theatrical versions that he could get his hands on, and he had them all destroyed. Which means that when Lucas said back in 1997 that the original theatrical versions of the Star Wars films no longer existed, he was serious. He apparently tried hard to make sure of it.