It's always hard to compare shows from different eras. Perhaps DSN pushed it as far as it thought it could get away with. Fast forward a decade later and because previous shows pushed the boundry a new show tries to push the boundry a little more.
I can see that. I also think its because its Star Trek. Because Star Wars and Gundam came out in the 70's and both were able to do war much more dramatically. In some ways I fear that the issue was that the writers were too TNG which was a peaceful non-violent exploration show. Writing for war was out of their area. One sees the same issues when they attempted to do the Ent world, which was supposed to be gritter too.
I liked the Xindi arc from ENT. However it did feel like a lite version of a season of "24" which Manny Coto worked on for several seasons. The problem with the way they handled the 3rd season of ENT was there was too many diversions from the main arc. There was no need for a Cowboy episode, there was no need for Archer to be transformed into a primitive alien ape like being. They could've spent more time covering both sides of the Xindi war and the intricacies that come along with it.
Star Wars is more Science Fantasy Action Adventure than war drama IMO. As far as Gundam, they're a full blown war drama using humanoid robots as a focus. They've had 30+ years to refine their formula and explore different territory. It's completely different with Star Trek since they didn't have experience dealing with a war drama arc until DS9.
Considering the fact that Berman didn't want to do it and kept meddling, I think the Dominion arc pushed the boundaries for Star Trek. That's why in ENT, we were able to even get a Xindi War.