I disagree with the sentiment expressed in the article.
To me, what made Trek great was that it was more than TV show: it was a vision.
It was idealistic, yes, but it wasn't pointlessly idealistic: it was giving us a grand dream of a bright future.
Just listen to Dr Michio Kaku talk about future tech or space and invariably reference Trek, listen to his enthusiasm.
That's what made TOS & TNG so great: they did extreme (especially TNG) idealism right; which is extremely rare in entertainment.
Comparatively, it seems to be easier to make quality "dark & edgy" works than idealistic ones.
DS9 seemed to be about undermining all of that. Yes, some episodes were very well made (The Visitor, In the Pale Moonlight, Way of the Warrior*, Inter Arma enim Silent Leges,...), but the near-constant undertones either undermining Trek's pre-established ethos or pushing religiosity, it seemed to be trying very hard to be the "anti-Trek" Trek series.
And in doing so, it became "just a show". Entertaining, but nothing more. Certainly not inspirational, unlike the prior series.
I don't agree at all. I think DSN was deconstructing
the Trek paradigm, but that by doing so, it was also reaffirming it. I find DSN's firm insistence that a better world will be harder than we think but is still possible to be more inspirational than early TNG's flippant belief in its own characters' moral superiority.
And I think TOS was much more like DSN than TNG in its skepticism of flippant utopianism.