While I'm actually on board, at least in part, with your point, there are some problems with the Statue of Liberty example you gave:
1) While the design and such could be traced to one guy, we're pretty much talking about something from one nation to another, not (arguably) the vision of one person to the public. We're usually a little more understanding of giving the rights to an individual over a nation, however right or wrong that may be in certain situations.
2) There is only "one" Statue of Liberty in your example. Changing it would destroy the original. Lucas can make as many versions of Star Wars as he wants, but the original will still be available. The Holiday Special still exists, after all.
3) It would seem to be a bit of an infringement on freedom of speech if we denied him the ability to do what he wishes with Star Wars, especially if we're going on the "Star Wars is public domain" argument, no?
I admittedly am not as vehemently upset over his revisions as most old Star Wars fans are either.
As for the movies being remade in 3D, I can't say I see it "destroying" the franchise, but I've never seen what's so great about 3D either, so I'm pretty indifferent.
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