It's not just that. Originally the AI voice in Her was played by someone else, but Spike Jonze felt strongly that the movie wasn't working and recast the part to Johansson. The movie immediately worked much better and became a sleeper hit. Johansson just has a much better fitting voice and higher skill in voice acting for this kind of role, to the extent that it maybe was a make/break choice for the movie. It isn't a surprise that after having created the exact tech from the movie, OpenAI wanted it to have the same success that Jonze had with his character.
It's funny that just seven days ago I was speculating that they deliberately picked someone whose voice is very close to Scarlett's and was told right here on HN, by someone who works in AI, that the Sky voice doesn't sound anything like Scarlett and it is just a generic female voice:
It's funny that just seven days ago I was speculating that they deliberately picked someone whose voice is very close to Scarlett's and was told right here on HN, by someone who works in AI, that the Sky voice doesn't sound anything like Scarlett and it is just a generic female voice:
https://news.ycombinator.com/item?id=40343950#40345807
Apparently .... not.