Perhaps we can best move forwards by dealing with some concrete examples. So long as there IS a level above which you're willing toa ccept my rights, that some things fall below it isn't as bad.
Here's my restoration of Left Hand Bear
http://adamcuerden.deviantart.com/art/Left-Hand-Bear-Oglala-chief-190160390
And here's the original. As can be seen, I have had to do reconstruction work in all four corners (as well as a hell of a lot else, but let's leave that aside for now)
http://www.loc.gov/pictures/resource/ppmsca.15973/
Can we at least agree that if major damage can be seen at low resolution in the original that I can claim copyright?