It's all downside. I've seen cases where this is used to 'give murder victims a voice' recently, both on CNN where they 'interview' an AI representation of the victim and in court, where one was used for a victim impact statement as part of the sentencing. Those people would laugh you out of the room if you suggested providing testimony via spirit medium, but as soon as it comes out of a complicated machine their brains sieze up and they uncritically accept it.

What are your thoughts on James Earl Jones giving license for his voice after his passing for Disney to use for Darth Vader? Or Proximo having a final scene added in the movie Gladiator upon the passing of Oliver Reed during production?

I see both of these as entirely valid use cases, but I'd be curious to know where you stand on them / why you might think recreating the actors here would be detrimental.

We have an actor dress up as $historical_figure and do bits in educational stuff all the time. Changing that to ai generated doesn't seem all that wrong to me.

Maybe there needs to be a rule that, lacking express permission, no ai generated characters can represent a real person who has lived in the last 25 years or similar.

I agree, though I think creating AI simulacra of living people against their will and making them say or do things they wouldn't is in some ways even worse.

Not my upside, but there is a big one: money.

Because it's easier than doing it without AI.