More's Utopia had slavery and capital punishment. Plato's Republic was ruled by an unelected elite that systematically lied to the populace. Trying to cram every conceivable 'good thing' into a theoretical society and say utopia is impossible because because some malcontents remain is silly. That's like saying we can't calculate the circumference of a circle from the diameter because we can't derive the exact value of pi. Rubbish! If the anti-utopians quit pulling straw men out of their behind to 'prove' the impossibility of utopia and utopians quit avoiding hard headed practical analysis in favor of fuzzy wooly feel good new age thinking maybe we could get some where. Perfection shouldn't be necessary nor 100% happiness and satisfaction. Technically the US Constitution was a stab at a utopia, based upon the knowledge and political realities of the time. What would serve as an equivalent in today's scientifically advanced, and cybernetically enhanced world? That's what we should be looking at as a model for utopia.
I do not think a utopian society is possible even when the citizens are all willing. The idea that every person participating in making a society will be perfect is a bit unrealistic. Even with same-like minds, there will always be problems and issues that are going to be apparent.
I believe even the most willing participants will start to have conflicts and issues with one another after awhile it's human nature to create conflict over minor and major things, so even if the society starts out as utopian over time it will gradually break down and eventually completely collapse.
A Uopian society is not possible by combining will participants. In order to achieve a Utopian society all members of society must participate and the wealth of the country must be evenly distributed among the citizens of the country. If there are unwilling participants, such as those who make very large incomes and do not want to share their wealth with poor participants, then the idea of a Utopian society will not work.
No, a utopian society is not possible by combining willing participants, because as long as humans are humans, with their broken natures, we will never be able to have a perfect world. There will always be a person who can invent more, or a person who is discontent with what they have.
No, no matter how hard you try you are not going to have a utopian society. There is always going to be a whole lot of trouble in a society and there is no way out of it. I think that the best societies just know how to handle trouble.