Your "blinders about human nature" are nothing more than a philosophical disagreement. Now we live in a world where every TV show is either CSI, or a reality show of mid-to-low-IQ people conniving against each other. Are these shows a better representation of humanity?
I think the Bird was right. The TOS and TNG crews were doing what they loved, and when you get a group of people together on a project in those terms, you do see a lot more cooperative spirit - not perfect, but it really does flow a lot like an Enterprise crew.
It's when people are forced into work they dislike, for scarcity and survival, that the pressure of that builds up over time and the behavior is far worse, staff are late, negligent, etc.
Admittedly, Roddenberry's vision was aiming high. That was the point. That IS Star Trek. Its not about aliens or phasers or any of that fun stuff we love.
Take the Utopian/Humanist vision out of Star Trek, and you've lost the vital soul of it.
As for Berman, I disagree with some of the decisions, but at least he understood what Star Trek is about and kept it whole.