You didn't see the boxes in 77, because with proper levels, they wouldn't be visible and them being visible is a side product of the telecine. But those are garbage mattes, not matte lines, that's something completely different. So when you say you want to be transported back to 77, you're effectively saying you'd like to see the film restored to as close to the way it looked in theatres in 1977 and the original optical composites are a part of that. And the film would have to be cleaned up to account for the ageing but not a step further.

It seriously frustrates me, that even here so many people would like to see the recomposited FX in an OOT restoration, because the original FX are a huge part of the film's historical value, they were a great achievement at the time and redoing them in a computer totally takes that away, the matte lines and extra grain are just a natural part of the special effects technology of the time.

Today, it would be possible to recreate the FX shots with CG, to make them look exactly the same but in higher quality, which would effectively be the same kind of thing as recompositing them.