While kind of tangential, I’d like to say the Culture novels do, in fact, largely follow stories of humans with complete agency over their destinies, and often human choices almost entirely shape the story. Minds do take a large role, in some novels more than others(Excession of course being almost entirely dependent on the decisions of Minds).

With that said, I don’t think it’s realistic to assume we would ever choose a Federation style society without widespread use of AI. The value proposition of AGI is too high. I don’t know if Roddenberry genuinely didn’t expect AGI to be realistic or if he chose to omit it as a stylistic choice(leaning towards the latter because of Data).