And in doing so, it became "just a show". Entertaining, but nothing more. Certainly not inspirational, unlike the prior series.
It all depends on what you find inspirational, I guess.
I find the characters' journeys on DS9 to be the most inspirational writing in Trek. I like TNG and TOS a lot, but the way DS9 took what had been done on those shows and challenged it, struggled with it, rejected some of it... It's a lot healthier, really, as a way of looking at the world than some of what TNG had to say.
So you admit that DS9 stands above the rest because their was a great conflict to define the characters, settings and Trek universe? If all it took was conflict to explore the human condition, we would have a million clone shows on television.
That's like saying everything TOS has to be 'Balance of Terror' 'A Taste of Armageddon' or 'Doomsday Machine' deep, dramatic and powerful.
For TNG all you have to do is ask every episode to be 'Chain Of Command', 'The Wounded' or 'Yesterday's Enterprise'.
Hell Enterprise did what DS9 did in it's 3rd season when they were trying to make it dark, violent and dramatic with the Xindi. It's not challenging to do. War and or large scale conflicts breeds development because the protagonists are constantly threatened. It give the heroes multiple chances to be brave.
As far as growing with the characters, sure the characters grew since the pilot but when you have 176 episodes what do you expect. If you analyze which characters actually grew and changed you'll find it's only Sisko, Kira, Odo, and Bashir. Dax changed when she became a new Dax, Quark was always Quark just the layers were peeled back, O'Brien was O'Brien, Worf regressed IMO.
What sets DS9 apart is the journey of the show. From Emissary to What You Leave Behind. Being stationary we saw the character's day to day and knew them intimately almost. That's what makes DS9 so strong. The needle was threaded well into a great story. A significant amount due to what JirinPanthosa said DS9 capitalizing on TOS and TNG foundations laid.