The original OT was worn out for a very simple reason: it was a widely popular film.

Eventually, after you make a large number of release prints, your internegatives and interpositives are going to wear out so you need to go back to the original negative to strike some more. Add to the fact that they may have used the OCN for the IB matrixes or perhaps to make a 70mm blowup interpositive, you’re creating a lot of damage. Then you have to remember that the film was shot on fading 70s filmstock and the effects shots were composited on notoriously unstable film in order to save time… All of these are a recipe for a very worn out negative.

There are lots of stories of popular film negatives being worn down: The Godfather is another example. During the latest restoration, the restorers found massive sprocket damage and one shot of the Don laying on a bed breathing was so worn out, they had to go back to the dailies and find an unused section of that shot and line up his movement perfectly.