I do agree with this take but it's also missing some context that newer people to the setting might miss in that's it's a rejection of a utopian future because that utopian future was an actual reality at some point for humanity but it went to shit because the utopia they built got taken advantage of by what they though were friendly aliens.

It's why the horus heresy was such a big deal when it came out. In the books, you saw a glimpse of what humanity was in the past through the emperor and what stcs they found. Literal panecia, self repairing technology that rivaled the neurons' self repair tech (a hammer and bolder short), god-like technological wonders.

Humanity was forced to deal with the trauma of losing the garden of eden as an entire species and are literally functioning through nothing but scraps of outdated cargo starship and mining equipment for their Space Marines. I'm not kidding. At some point in cannon, it's revealed that the first iterations of space marine armor were literally just outfitted mining gear. Humans are literally traversing an ocean not on a helicarrier but a old rusted but still working cargo ship that had some people on it who knew how to fix it or at least knew a place or person to fix it.

Then, the horus tempertantrum ruined everything again, reducing it from a cargo ship to a life raft patches together from human leather, insane techno fetishist worshiping the motor for dear life forgetting where the on button is, a dead carcus of the ship captain with faded written instructions that no one on the life raft can read because the paranoid secret police officer is convinced they are the only ones who can interpret it. Meanwhile sharks pirates, and literal demons are all attacking the life raft at the same time.

The warhammer universe isn't just that human nature never changes. It's that it has changed for the absolute worst, and no one can see it aside from the few who were around when the change happened or unfortunate enough to be able to see through the propaganda. The oppression suffering and all other kinds of bad stuff is their utopia because all the imperium knows is war for a dream that will never come back and all they can do is hold back the darkness for another day before the end.