I think the reason there are still jaggies and shimmering remaining in the image is that the instability combined with the low resolution results in some details ending up on completely separate lines, which could well be beyond fixing.
Plus the vertical blur Lucasfilm added to the DVD to hide the problem only exacerbates it. Even though the LD Definitive Collection suffers from the same issues overall, it seems the aliasing cleans up a tiny bit more.