Hmmm... Even films are being digitised and remastered. I don't know if all artworks are for sure diluted but I could see your point. When you update or digitise an artwork, it's like your taking away what makes it unique. For instance, with films, although digitally remastering them makes them more clear and crisp, you're taking away the vintage aspect of it. Because for me, that's what makes older films good, the aspect of it being vintage.
And with artworks, it's the same. You need to show exactly how it was done for people to realise that it took real talent and effort for these artists to bring their art to life. When you digitally master it, you take away the artist's persona in it. Some aspects are lost and most of its flaws are removed. As we all know, the flaws make up the part of the art itself.
Of course, art like ancient buildings or even churches need somer restoration at one point. Maybe a storm has ruined or destroyed them. In those cases, restoring them is the only solution for saving them.