So the Darth Vader AI thing in Fortnite is relatively harmless (except for ecologically, perhaps), and is mostly one of the currently few ethical ways to be implemented, after James Earl Jones consented to signing off his voice for use in future shows (with perhaps some additional use with real voice acting).
However, its current use is why you can't beat real voice acting.
When you address him in game, he replies in a cold monotone. There's no inflection, no intonation, just a flat reply. Even in the movies, including Rogue One, in which he made a brief appearance, you could tell it was really James Earl Jones doing it.
He's such an emotional response. James Earl Jones actually doing the voice in the movies has such a dark, deep, almost bleeding, like a cut, sort of voice. He's not friendly. He's not your friend.
AI Vader in the game, as ethical as his use is here, still only sounds like the spoon pickaxe he came with.
I really hope they don't use ai voices in place of real people for characters, even though this implementation of it is the least harmful. However, you just can't beat real voice actors, for real.