Yeah, I noticed that many years ago (largely courtesy of DS9, as you pointed out.) It's easy to be a saint in a technologically-produced paradise of unbounded resources.So ultimately, it's just a very poor guide for humanity. "If you have everything, you don't need to worry."
Even then, humanity can't just stay at home and play with their replicator- and holosuite-manufacutred toys. No, they must "explore" the cosmos, which ends up being equivalent to tromping on other people's turf, which incites conflict. And then Starfleet stands around blinking in wonderment at the perplexing viciousness of their alien neighbors.
So Star Trek's true message about human nature is, even when we have everything we could possibly want, we want more, and will make trouble for everyone because it's our nature to do so. Yeesh. How is that positive at all? Hew-mons might as well be Klingons. At least the turtleheads know how to throw a party.