I think it's more like the other way around - DS9 is light compared to Babylon 5. I've heard that the DS9 writers were forced to up their game for later series after seeing the epic story arcs that B5 was doing.
Yeah-- B5 did heavy stuff and had a preconceived story arc, while DS9 started off doing the same old Star Trek thing, planning for eternal syndication, stuff not really particularly in order (so the shows could be broadcast in any order depending on the station syndicating it) and resetting things at the end of every episode.
B5 was one of the first shows to take the form (episodic TV) and make it actually episodes in a story with a beginning and end, and that pretty drastically changed the feel of the show and made it feel like stuff that happened in each episode _mattered_-- unlike DS9 or earlier Trek shows (although TNG put a little effort into trying to make stuff matter, sometimes-- the episode where Tasha Yar died for no obvious reason was sort of an attempt at that, I guess).
By structuring the show that way (or adding structure at all), B5 changed how television worked. We wouldn't have had The Wire or Breaking Bad or any number of other more-recent shows if there hadn't been a B5 to demonstrate that episodic long-form story arcs could work on television and that TV producers had (to nobody's surprise) been underestimating the viewing public all along.
You're being too unkind to DS9, and too kind to Voyager. Even moreso than TNG, episodes in DS9 carried over from each other. There are tons of events in DS9 that would make the show unpleasant to watch out of order, primarily due to all the wars. It wasn't as well connected as B5, but there's continuity.
Contrast this with Voyager: one single storyline that moves at such a glacial pace that each individual episode contributes basically nothing to the arc. When the story moves, and it didn't, it did so at such huge leaps (taking years or decades off of the journey) but since there's no apparent fatigue from it, there's no consequence. And every Voyager episode was wrapped up with a very neat little bow. All of them. The Year of Hell should have stuck, god damn it! It would have at least made the show interesting again!
Enterprise kind of did it better. The temporal cold war was dumb and incomprehensible but it was there. The war with the Xindi was dumb, but other people liked it. And when they jettisoned all of that crepe in the last season and started to get on with connecting the show into established Star Trek history, it was immensely better.
I really need to finish watching Babylon 5.