With due respect, this started with TNG and DS9. In TNG we had the introduction of the Borg. Previously alien species had demonstrated that many of Trek's problems were solvable with technology. The Borg were Technology run amok, taking over people and damaging individualism, as well as creating the fear of your friends being turned against you. DS9 continued this, showing the fringes of the Federation, the poverty, the failed colonies, and the difficulties of the several wars that TNG had highlighted. The Maquis were another reflection of the factionalism. Even Vulcans in TNG could be infiltrated, and then DS9 reflects this further. Finally, we had the war with the Dominion, were your friends could already be turned against you. Utopia was already deconstructed.
With due respect, the human race has always been this way. Study history and you'll discover just how disgusting humans are capable of being. We are a savage race, with a thousand years of violence behind us. But we're not going to kill today. I don't think we are more disgusting; I think we're more practical. Don't tell me about an ideal without showing me how to get there.
This cuts closer to home for me personally because I work with kids who sometimes feel violence is the only answer. They feel they have no other choice to be heard. Telling them that things will become better is a hollow platitude. Acknowledging the emotion and creating choice, even if it is just as simple as reaching out to myself, or another mental health professional, a peer, or someone, as long as they have choice makes violence less likely. It makes community more likely. It builds honesty, acceptance and cooperation, rather than isolation and being told "You're not good enough to be in this group. You're not smart enough, clean enough, healthy enough. You don't belong in utopia."
We need the ideal, but more than that we need people who are wiling to say "You're accepted here, warts and all. Pain and all. " Don't tell me about utopia; tell me how I can live with myself today. Will you take my hand?