I've done the Oasis and Swamp now and honestly the quests in both were the same boring, MMO-like slog as the Hinterlands. I don't see much difference. The main quest does improve, for sure, but the side content is the same boring crap.
I would love if someone would address this. This has been my experience so far as well. I have cleared most of the Hinterlands and all (I think) of Fallow Mire. The main quest is decent so far (collected Dorian as a party member), and the world absolutely OOZES character, but the majority of the side quests feel rather flat. I am okay with fetch quests and, "go kill this," quests, but so many have minimal story, and little to no dialogue.
For example, in Fallow Mire, there you find a scrap of paper in which an apostate writes about finding a powerful demon, and a quest is put in your log. Why do I care? The world is drowning in demons, why chase this one down? None of your party says a word. You eventually find his campsite, and kill him. Quest over, no dialogue, no options for resolution of the problem, nothing. There were a few other quests in Hinterlands that I did not even know I was about to complete it when the, "quest complete," marker flashed up on screen. The hunt 10 rams quest was acutally one of the more fleshed out quests. Some are barely more than telling you to move to a particular point on the map (find X landmarks, I'm looking at you).
The key is in the details. Players need a context to do the quest in. We (most of us) want dialogue and story behind our quests, more than three sentences of text on a scrap of paper that don't even tell us WHY we should do the quest. What I think people are complaining is that some of the quests feel very much like quests seen in MMOs (such as SWTOR), which offer tons of quests with little real story. Yes, there is some smidge of context to each quest, but not much meaninful dialogue or interesting quest progression.
Having a large, open world is nice, but some people would like a slightly smaller world with a few less quests, but where each one is really fleshed out and meaningful. Each side quest should feel, "hand-crafted," and well thought out. Hopefully someone can chime in here and state that side quests are more involved and complex in other areas, but after two large areas, I haven't seen it yet.
Don't get me wrong, I am enjoying the game, but it feels like it was made into a large, open world game just because gamers tend to drool over open worlds for some reason. Bioware's games usually lend themselves to more linear (branched) quests, and I think that a more controlled, paced, but fantastic and meaninful story/quest with equally meaningful diversions, would be the best.