I would not call Deep Space 9 a dystopia. Nor Babylon 5, for that matter. They are not happy places to live, for sure, but both settings are abundant in hope and possibility.
That the writers at this point in Trek canon started playing pretty fast and loose with Roddenberry's vision doesn't erase the deeply optimistic and even spiritual grounding of that show.
Also worth mentioning the recently deceased Walter Koenig who had said that playing Alfred Bester in Babylon 5 was his favourite role, despite being much more famous as Chekov in the original Star Trek.