Just to add to what you already pointed out, I think that the overall story line of Inquisition is part of the problem as well. The first half is fairly solid, but the whole plot line seems to unravel after "Here lies the Abyss". It seems that DAI suffers from being bloated with content that doesn't really have any plot relevance. Although DAO and DA II are not as robust as DAI in terms of sheer size, their main plot lines and subplots are much more integrated into their overall plot. While DAI has numerous zones to explore, the side quests within these areas don't tie well into the main plot and the current world state. What plot relevance does the Storm Coast, Fallow Mire, Exalted Plains, Emprise du Lion, Emerald Graves, and the Hissing Wastes have? Nothing we do or accomplish in these zones have any tangible consequences towards the main plot. In consequence, our sense of urgency for dealing with the Breach is lost due to being overloaded with singular dead end plot lines that do not weave into the larger tapestry that is Inquisition's story.
Unlike DAI, each major zone in DAO, (the Circle Tower, Bercilian Forest, Red Cliff, and Orzammar, contributed to the overall plot by having us rally an army to deal the Blight. Even though these zones had their own subplots, they are still related to the overall plot issue which was the Blight. We we're never sidetracked from our primary goal since we had the catastrophe of the Blight on our heels. Comparatively, the threat of the Breach is never felt though these different zones in DAI since they are in themselves their own isolated stories.
Because of this lack of focus, DAI story is comparatively weaker than its predecessors. If DAI was able to integrate the subplots of these zones into tangible consequences that effected and related to the main plot, I think DAI would have been a narrative thrill.