It just feels wrong to let a machine finish something the artist never got to complete. They can't approve it or change it, so it stops being their vision and becomes someone else's guess.
I guess you could say the art gets finished, and that might be nice for fans. But what makes it theirs is the choices they made, and a machine just guesses. Maybe I'm wrong, but that feels different.
That's a fair point about The Crow, and I get why it worked. But those were real people making careful choices, not a machine guessing. I can't really argue with that, but it still feels different when a computer pretends to be the artist.