It may be immaterial whether we call Culture a utopia or a dystopia. I haven't studied Banks' works in exhaustive detail, but the impression I got is that people in the Culture can do almost anything, because none of it matters. And if it did matter, they may have no agency to do that. So the Special Circumstances could have been created to accommodate people who want at least an impression of some agency (while - from a vague memory of one of the Culture books - chasing successfully a list with what turned out to be coordinates of all stars in a region of space).

I got thinking about this aspect of Culture starting with a broader premise - are there works where humans arrive at higher levels of human-embedded intelligence as a species or in a more limited scope as individuals? While describing higher levels of intelligence may be impossible, I find it curious science fiction doesn't appear to have too many attempts at that. Some of Vernor Vinge's works come to mind, but even there humans appear to be about the same as at present.