I think for better or worse, old films are what they are, and using AI to remove grain and add mutant faces is a terrible idea.

But I'm not anti technological progress with film. You've cited some good examples here (for example, The Wizard of Oz). Here's a piece I wrote defending good use of CGI, for balance. :)

Ten Landmark CGI Films | Fanfare

By the way, that story you send with the painting of Jesus ruined — wow.