Another deeper reason is since the Cold War there is this conscious attempt to reduce art as the one-sided activity of pure self-indulging expression of the individual, instead of an active process of collective reflection and engagement. Visual art in particular is about "expressing muh true self" instead of reproducing the social reality for the wider society that one is merely a part of. This is why the people most outspoken against AI are wannabe visual artists. Even the "quality" and reception of their art do not really matter to them (they will look at your face and proclaim their trash furry porn is superior to even the most sophisticated image using gen AI), it is all about the joy in the sanctity of the process itself.
In contrast, films are inherently industrial and constantly self-revolutionizing. Further, most honest film directors know their work owe their existence to all the other works they have watched during their youth, especially the New Hollywood generation. They don't pretend their artistry is the product of some ex-nihilo "creativity." Directing and filmmaking are more like a craft with evolving lineages that they inherit from earlier filmmakers who themselves were relentless experimenters and constantly remake the filmmaking process. Scorsese's passion in promoting and restoring older films is entirely consistent with his embrace of gen AI.
Much of the backlash against AI is really just the consequences of the big post-2008 GFC cope sold to millennials that โcreativityโ is somehow this thing held in reverence that makes it worth it to be at the bottom of the employment pyramid.