Sociologically, the modern and postmodern conditions are pretty complex, so I think you're being somewhat simplistic in your reductions.

Maybe postmodernists adopt too high standards to use them as excuses to be cynical when those standards are never achieved.

But I suspect that lots of postmodernists would say they understand our fallibility very well, which is why they treat all discourses as mere halfway fictive literature. Postmodernists branch off into indecipherable prose poetry because they think all we're doing is telling stories anyway, even in science. If only literary or aesthetic criteria matter, why not try to be creative in your writing? So their obscurantist style is consistent with a dramatic affirmation of human fallibility.

Again, here I'd critique postmodernism. I think modernists went too far in their presumption of perfect objectivity and neutrality, while postmodernists go too far with relativism, cynicism, and antirealism.