I think it more of a perception thing.
When we talk capitalism, for example, we expect people to lie, cheat and steal. They do. We aren't especially upset because we expected it. When we talk military dictatorships we expect ruthlessness. We get it. We aren't especially disappointed because we didn't expect better. And so on.
When we see these same human characteristics in more utopian settings, we should be no more surprised. But we are. But what happens next is something odd - and I would say wrong - we condemn utopian aspirations.
Think about it. How many times have you heard people say things like "it's always people with the best of intentions who cause the most harm"? It isn't true, of course. But it's either taken as great wisdom, or a truism.
At the same time, our whole society is built on this interesting belief