I don't necessarily *mind* the open-worldness, but I do feel that in DAI, because the open-world is filled with mindless, boring, fetch-quests it does little except detract from the story. Also, the mind-numbingly quick respawns make it difficult to actually go and enjoy the world.
Basically, to me it seems almost like 2 different games squished together into one game in a way which really didn't work: There is the main story, and then there is just tons and tons of random junk filling up these lovely areas. If each of those areas had just two or three fully-developed story-line (immersive) quests instead of all the junk quests and combat, I think it would be a much better game. (Heck, put in a respawn-timer-preference, so that people who like fighting the same fights over and over every three or four minutes can do so, but don't force everyone to grind through that crap!)
It's just kind of a disjointed mess. I think maybe the best open-world RPG recently would be Fallout 3. It was open-world, and often what you were doing didn't directly have anything at all to do with your main quest, but somehow the melding was done so seamlessly that it worked very well. It's hard to pinpoint exactly why it worked so well - maybe it's simply because you are established from the very beginning as a character who should be completely fascinated with the world outside the vault. The urge to explore absolutely everything seemed like an integral part of your character's personality, so the exploration never seemed unnecessary or like sheer drudgery as it so often does in DAI. If something similar had been put into DAI, I think a lot of us would get more enjoyment out of the basic exploration. (Plus, if everything didn't respawn at least you would have a sense of accomplishment. As it is, I just can't find any real justification for, or enjoyment from, unnecessary exploration.)