Just because the changes don't always effect the overall story doesn't mean they don't effect the film. The Special Edition version of Star Wars grinds to a halt once the characters reach Mos Eisley — too many unnecessary additions and an additional, redundant scene — which unwinds somewhat what was formerly one of the tightest sections of a very tightly structured film. Vader getting his shuttle at the end of Empire totally disturbs the pace of the otherwise white-knuckle “Hyperspace” sequence and don't get me started on “Jedi Rocks.”
Replacing the sequences in the last battle in Star Wars always struck me as being somewhat disrespectful to the people who developed new methods of achieving those original, ground-breaking special effects and then spent their entire days and often nights realizing them.
My father said that leaving the theater from seeing Star Wars in 1977 and driving home, he felt that he shouldn't be driving, but swooping and diving. That's the effect the original effects had on the original audience, and that's why the original versions of the films ought to be preserved.