First, consider the fact that many of the texts you mention include significant apocalyptic elements, too. In fact, imminent judgment is a major theme in the majority of the works you describe.
From Isaiah 6:8-13:
And I heard the voice of the Lord saying, “Whom shall I send, and who will go for us?” Then I said, “Here I am! Send me.” 9And he said, “Go, and say to this people:
“‘Keep on hearing, but do not understand;
keep on seeing, but do not perceive.’
10Make the heart of this people dull,
and their ears heavy,
and blind their eyes;
lest they see with their eyes,
and hear with their ears,
and understand with their hearts,
and turn and be healed.”
11Then I said, “How long, O Lord?”
And he said:
“Until cities lie waste
and houses without people,
and the land is a desolate waste,
12and the Lord removes people far away,
and the forsaken places are many in the midst of the land.
13And though a tenth remain in it,
it will be burned again,
like a terebinth or an oak,
whose stump remains
when it is felled.”
The holy seed is its stump.
Obviously, that's quite different than what you'd normally expect from a work intend primarily as a utopian work.
As for whether the "golden age for humanity" is utopian, I suppose that depends somewhat on your view of the text and your definition of utopian work. Some of this depends, too, on your view of the relationship between authorial intent and meaning, so feel free to disagree with me on this point, but I think that there's a real sense in which the author has to actually intend a utopian (or dystopian) work to be that. For example, books like 1984, The Hunger Games and Atlas Shrugged are clearly dystopian fiction, but in all three cases the authors were consciously writing dystopian fiction for the purpose of engaging in social commentary. They are also, in some sense, counterfactual: Suzanne Collins doesn't literally think that the government's going to start running annual Hunger Games, but that's not really the point. You can say the same for utopian fiction, actually. I really don't think that that's what's going on with the texts you mention, though; while they certainly make heavy use of hyperbole and metaphor, I don't think that the authors were really intending the texts to be completely counterfactual in the way that you'd usually see with utopian or dystopian fiction.