I know Brayden with Mickey Views is sometimes frowned upon here, but he said he heard from a friend in Imagineering that the problem isn't the projectors or the screens, it's the glasses. They're apparently very expensive to make because they wanted them high quality for the ride. Over the years, they would replace damaged or stolen glasses with part of their bulk supply from their initial purchase. We've now reached the stage where the bulk is gone and executives haven't been willing to purchase more (at least not yet), so the scuffed glasses are what we're left with, which creates the visual issues.