The no generative AI statement is a bigger deal than it is being treated as
Most studios this year have either said nothing on this or given a carefully worded answer that leaves room. Rockstar gave a flat statement.
What makes it notable is the scale. Six hundred thousand hand made animations, over fifty commissioned artists for murals, years of location research. That is a company demonstrating the claim rather than asserting it, which is the only way anyone should be evaluating claims like this.
I do not think it makes the game better on its own. I think it tells you what kind of production this was.