As far as growing with the characters, sure the characters grew since the pilot but when you have 176 episodes what do you expect.
DS9 is the only Trek show that really has this, or at least it has much, much more of it than the other shows. It's hardly something that can be understood as a given.
DS9's writers were actually really good at building characters, challenging them, and tying together disparate plot threads in ways that were essentially character-driven.
The show compares favorably, in that regard, not just to other Trek shows, but to other shows in the genre, and even outside of it.
Where serial story-telling is concerned, DS9 is pretty amateurish. It's better than other Trek shows, and it's good that the arc episodes are there, but there isn't really much of it, and what's there is far from perfect. DS9's strengths are really world and character building.
Not all of the characters have Kira, Odo, or Nog-like arcs, but they are all affected by the journey in one way or another. Quark is a good example of that. In a sense, his journey is "staying the same," i.e. not being assimilated, not going soft as he puts it, or not completely. So Quark and his bar end up almost like the station itself: the main stable element. But the Quark of WYLB
is not the Quark of Emissary
. The difference is just more subtle than wth, say, Nog.
Why? Because Quark has had his initial views and values challenged in a hundred different ways since the pilot. He still has them, but he understands them differently because of those experiences. One could say the same thing about how DS9 challenged some of Trek's core ideas: they survive, and in a sense they are stronger at the end of the show than before. But we understand them differently.