Except CGI, which were often rendered to a specific resolution but transferred to film. Restoration efforts or remasters then have to redo those effects, and often the source of the effects were lost because never archived and shared.
Also, some restoration of old black and white films with AI upscaling try to counteract bad early films or films that degraded.
Indeed, all post-processing will need to be done again, and sometimes they do a questionable job, like in the case of Buffy the Vampire Slayer. So there is a lot of challenges with a remaster.
Still, the possibility to extract more information is there, which is a plus for film. With AI, I feel the opposite. I like it that it's fun, but I dislike it that AI creates new information. What's again exciting for me is the possibility of extracting information from a moving picture from movements, and over time. I think these two angles are currently under-utilized, but hold much potential, once we discover more techniques and throw more processing power over the problem.
Also, some restoration of old black and white films with AI upscaling try to counteract bad early films or films that degraded.