So the unaltered frames, even if they still existed, are in 15 years worse shape now than they were back then. And remember, we're talking '70s film stock, which wasn't the best film stock to ever grace the film world. And I'm mainly talking about ANH here.
I take it these guys have never heard of Star Trek, a television series that was also made using film stock but was filmed during the 60s.
That got a HD master (or whatever you call it) from the original prints a few years ago and they look pretty darn good. And the film stock for that were probably in worse shape, maybe.
Also, although they updated the effects for those episodes, they also enabled people to see the episodes with the original effects in the same High quality as the live action stuff.
(score one for star trek).
Examples of Trek HD stuff or whatever.