@holden I see your point, but I think the difference between the Venus de Milo and the Liberty Bell is that the Liberty Bell’s crack is part of its story, making it more impressive. I’m not sure that the Venus became more impressive just because it misses arms. As for the Sphinx, I don’t think its knocked off nose makes it any better, but it does remind us that the civilizations that came after the Ancient Egyptians wanted to show their disrespect and so intentionally damaged the Sphinx’s face. That kind of lends more of a historical perspective to it. I like @Jeruba‘s idea.
Tough call, because those arms ain’t coming back.