The furthest I have ever been in the game is the defence of Haven. I just get fed-up, bored, as I do in many mmo's.
In short, that tells me you're doing it wrong. 
You should reach the defense of Haven very fast. That way you get access to more companions faster, and the game does get better, IMHO, after that point. "In your heart shall burn" was a kind of a watershed event that did a lot to get me more involved in the story.
So don't spend inordinate amounts of time in the Hinterlands doing side quest - that'll lead to the game feeling like an MMO. You can always return there pretty much any time later, should you feel the need to do the quests you skipped. Do enough to gain enough power to advance the plot - at least until you get past the mission "In your heart shall burn".
Essentially, there's only two things in the Hinterlands that, if you want to complete, you have to complete before the defense of Haven - defeating the templars and the mages that are fighting there. Those missions apparently become unavailable after the defense of Haven.
I DO get your problem with the game though. It can get tedious especially for the player who's a completionist by nature. It can be hard to walk away from things waiting to be done. 
I also do have to say that DA:I just doesn't have the "atmosphere" of DA:O or even the much maligned DA2. It's hard to pin down exactly why that is. DA:I was certainly harder to get into. I do like the game though, even if the Bioware "feel" is not quite there.