This is a very interesting discussion but I think it can also be a road block to getting a world that is good enough for your story. It's very easy to get stuck on trying to figure it all out before writing the actual narrative.
Figuring out what "works" in a fantasy world is somewhere between a great one liner to a lifetime of documents. Any student of history can tell you about the pitfalls humanity has been through so far and a psychologist or anthropologist can most likely describe all the challenges any group faces over time in terms of coherence or strife. Creating a detailed model of an utopia without possible faults is a challenge, to say the least. There are ideas though that tries to capture humanities needs. One of the more famous is Maslow's Pyramid. It doesn't really care for good or bad, but basically says that if we can cover our basic needs (protection, food etc) we can strive for other things (art, self realization and so on). A simplistic definition of Utopia would be the top of the pyramid for all the Utopians.
Morals and ethics - what is good - is another matter. It's probably easiest to stick with the big things (killing people and harming others) and keeping it in black and white versus going into all the shades of gray (is the harm of one worth the utopia of the rest: what faith, if any, defines a good life best?).
My personal view is that a world should not be more than the story requires and that one of the greatest traps for a writer is caring more about the world that is created than the tale itself. If you keep it simple, then you also make it pretty easy for yourself.
Space Opera is in my view a genre that leads itself very well to the simpler the better.
"The galactic empire had endured a thousand years of peace and prosperity, making hardships, war and suffering an unknown to all its people."
That's a space opera utopia in my opinion. If you want to introduce strife and conflict, then you add a line about whats outside the empire's domain. I would not really need more if I read a book. The premise of Star Wars does not require many lines of text. The beauty lies in the simplicity and the ease of acceptance. That is both the premise of the utopia and, most likely, the story. It's when you start explaining why it's been a thousand years of peace and prosperity that Pandora's box is flung open.
Lastly, if your story requires additional information here and there, add something simple that supports the premise. "Growth pods supplied all the foods the empire needed." What's a growth pod? Who cares! Because Space Opera!
PS. The simplicity of the premise can also help the story in other ways. That the Big Bad Person is evil is pretty clear, when their plan is to turn off all the growth pods. That means stopping BBP and turning them back on is good, as all the food of the Empire depends on it. Your value of your McGuffin does not require a paragraph to explain why it's so important. DS.