Utopia
I want to join the Culture.
Let's be honest: There is no real reason why one wouldn't want to join the Culture. No scarcity, no restriction, no death, and an apparent list of things you can do even longer than the one we have. I mean, lava rafting. Lava rafting.
Sure, life isn't perfect, because apparently the Culture is elitist and thinks they're better than everyone else and therefore they have the right to meddle in everyone's affairs "For the Greater Good" (very much an American-type culture), which causes problesm. Plus, they haven't made any progress on the sleep front. On the other hand: Lava Rafting. Or if that doesn't float your boat, you can spend the next thousand years studying giant beholders floating sapient blobs of flesh. And, assuming nothing catastrophic happens to your consciousness (which seems unlikely if you take reasonable precautions and the Culture doesn't attack the Idirans again, you get to turn into a fourth-dimensional energy being in a few thousand years.
Which is all very impressive, yes. But, the thing is, it's kind of dull. I'm not saying that Look to Windward is dull; I didn't enjoy it as much as I have a lot of the other books we've read, although I loved the sheer number of crazy concepts Banks came up with.
My point is that utopias are dramatically tricky things, and The Culture is just about as Utopian as you really can get. We looked at utopias once before, in The Dispossessed, but it's a completely different society in non-utopian ways; it's like comparing the living conditions of a peaceful Somalia to the United States (which many people said made it "non-utopian", to which I said that utopia was a government construct, not a material one. and while my memory may serve me as faulty (the Odonians were ascetic, but I'm pretty sure that was out of necessity), I think they'd enjoy living there. The Loonies would enjoy living there. The only obvous reasons people wouldn't enjoy living in the Culture are religious (not a good place for Buddhists, or Puritians) or psychological (not a good place for Paul "I'm a God made flesh who everyone around me obey's" Atreides; and even there, I'm sure that there's a sect of Buddhists living out in the Pylon badlands. This is a land where newspapers would go out of business if there were such things as expenses: the news would be "Taxes are nonexistent, no one was killed last night*, and everything is peachy" every day.
* Actually, I wonder if rape happens in the Culture? It's the one crime I can think of that's done against people that the Culture can't rectify, and it's not caused by material needs.
Which is great as far as living there goes. But, again, the problem becomes that when you've got a world where the stakes are rarely life and death, things are diminished. The potential for conflict is reduced to the petty; if Rachel dumps you, no one can get you to snap out of it by saying "How can you be worried about that when there's people living in boxes under bridges, eating nothing but a handful of rice and slowly starving to death?", because that's the life they chose. The only alternative is to have some outside source of conflict, which Banks does, of course. But a place which has so few flaws (beyond decadence, which is a charge with heft only if your decadence hurts someone in the process) is far more difficult for the center of a narrative than one would expect.
Just something to think about.
ADDED LATER
One of the sort of inside jokes about Watchmen is how it traces the evolution of comic books from the Golden Age (Minutemen) to the Silver Age ("Crimebusters") to whatever the modern age is called. I'm not a comic book person, but the way costume distinctly changes clearly is related less to actual fashion trends than comic fashion trends. There's also the concerns that the groups fight. The Minutemen fought crime. The only name we really get for someone they fought, Moloch, was basically a freaky-looking Tony Soprano with a "Solar Mirror Weapon", while the Crimebusters are called together to fight not "crime" (no matter what their name says", but social ills: Drugs, Riots, Anti-War Demonstrations, Black Unrest, Promiscuity, Campus Subversion.
Perhaps it's indicative that these are the social ills which kept America worried during the 1960s. I don't want to really address that so much as the idea that these are problems that Vigilantes can head off. Even the first on the list, something which (by an admittedly simplistic view) you can fight by going after the dealers-it's not something which really *calls* for a superhero. None of these are problems which can be fought symptom by symptom; the root cause needs to be addressed, and ad baculum isn't the way to go about it.
We never really see why the Kean act was needed, but I'd assume that's part of why: because there are only so many problems that brute force can directly be applied to. And a great deal more that violence only makes worse.