I think it depends on who is making the changes. When George Lucas is making the changes, people get worried, because he has a tendancy to make things worse these days. The updated Star Wars CGI was distracting cuz it didn't fit with the rest of the movie. Although it is his movie to mess with.
When Speilberg changed little things in ET, I had no problem. Even this isn't that big of a deal. But George has gone a bit soft as a filmmaker, so the idea that he'll really improve anything seems a little misguided, that's all.