And that long post accomplished what? It still isn't fact that DA: is meh or its side content. The analogy with cream is that I found the "filler" in DA:I to be more of what I wanted and the "filler" in TW3 only giving me more of what I already found to be an average game. Fairly similar amounts of filler in both. The issue is the bias that decides if it you like one game over the other. The side content in DA:I is not factually worse. So stop acting like it is.
"Accomplished." Attempting to reason with the sort that considers filler to be golden does indeed make such a term suspect in that limited respect. Fortunately I tend to speak to the matter, not the sort...
Much attention gets paid to the length of my reply. I tend instead to think in terms of "thoroughness" and "preciseness." How's that for relative? I have no time for filibusters, but I'll take the time to explain something more fully if it takes a while to do so...
The dichotomy is not "is DA meh or 'side content.'" False dichotomy. At least for most of us on this side of the dichotomy. It's "is the bulk of DA's side content meh?" As to facts(!!!) of the matter, I'll address this in my reply further ahead.
Your derision for TW3 is irrelevant to me. Perhaps you're 100% correct. Even more correct than you know. There is "right opinion" after all, wouldn't ya know. And you may be absurdly wrong. I wouldn't know, however. I haven't played TW3, haven't mustered the wherewithal to bother trying except a couple brief moments (despite buying the bloody thing). So the bias for or against doesn't apply to me. Actually, if either, the bias against TW3 is stronger with me. But I'm not "acting" as if that bias has any relevance at all. I'm a DA fan judging DAI on DA's merits as a franchise. You... aren't.
Well, except that it is arbitrary. What's the formal, agreed upon definition of immersion? Where is the survey that has a statistically relevant random sample of DA:I players responding to a survey regarding it?
We can investigate attitudes and tastes. But to do it objectively requires riquer. Posting a lengthy opinion is not rigeur. Seeming consensus might be - but there's no real evidence of any such consensus, because any audience we can point to is very self-selected.
Agreed upon definition by whom? And who is to agree that these agreers are sufficient? See how easy it is to make it sound insufferably arbitrary? Relativism is utter intellectual dishonesty. As to this "riquer..." uh huh. Is that French for "intellectual rigor?" (In which case I'd say I'm applying far more than you...) Referring to Alexandre De Riquer? (Likely not...) As it's a nonsensical term otherwise, I won't presume, but if only short replies show "riqeur," perhaps I'm right to mock it... As to the validity of "consensus," examine the "argument from popularity." Consensus is not sufficient either if you're sincerely looking for evidence.
And the reality it isn't so arbitrary, is it? A game that constantly jars the player out of a sense of identification with their own protagonist or their sense of the character being a part of the game's narrative, a living part of the fiction... yeah, that would be a game that breaks its players' immersion. Disagree? The most stark example of this is a buggy game. No way to maintain immersion in a game that crashes every 30 min. What is more objectively quantifiable than the rate at which a game crashes? Does one need to be "self-selected" as a judge in that case? You set the timer, you play the game, you record how often it crashes. Human tolerance for such a thing may vary, but a game that never crashes will be less immersion-breaking than a game that does every 30 min, no? I'll presume agreement (cuz it's the only intellectually honest response). And by extension I'll presume you agree that there are other objective criteria by which a game may be judged to be immersion-breaking.
In DAI's case it has only crashed for me an average of every 5-6 hrs (usually bursts of 3-4 times in a 1-2 hr period in a particular area), so that's not it. No, it's the mechanical nature of the side-quests in the... what? 60%? 80%? I said 95% earlier... of DAI I've done anything other than main or companion quests. That is, for the vast majority of the time of my life I've spent in DAI (which according to Origin/EA is apparently *gulp* 708hrs... (holy friggin...)), it's been spent in side-venturing. If side-venturing were 10% of my time, it'd be a different assessment, wouldn't it? (Which in my case would be about 71hrs...) This is where relativity as an assessment tool is more honest: the quality of my time spent in side-venturing is only an issue relative to the amount of total game time that side-venturing entails. Not to say that if side-venturing were shyte I'd be happy with it because it's only 2% of my time, but it certainly holds that while it at least feels like 95% of my time, it really... really... oughtn't to be shyte. And if I were to pretend that a completionist like myself finds only 50% (rather than 95%) of my total game hours are spent in hill-crawling and respawn grinding and craft material farming and side-quest fulfilling and exploring... that would still be roughly HALF of 708 hrs... And it's well over half...This is also why I suggested to the devs to simply limit the side-venturing content if they don't have the resources/staff/time to devote to fully developing that content. How unreasonable is that when side-venturing takes up in reality the vast majority of the total game time (unless you rush the main story)?
And this is where the "completionism is a disease to be avoided" type tries to say it's all my fault for trying to complete all the side areas. But really? They made side content to be ignored? One is a fool to go after it? Side-content is a trap? Well, that's a blight on the dev's record as well then for trying to trap people into wasting their time in side-questing... except that I'm presuming that's untrue. No, I prefer to think that the devs created the side-content with the belief (how subjective of them) that it would be... sufficient? meaningful? filling? I'll just say, "They meant well." I want to say that. Not sure what they were thinking, but it seems the height of cynicism to think they intended it all just to screw with us. There is content there after all so I'll argue against that. In any case, the game is what it is. It doesn't matter if I'm a completionist or not when judging a game for all it is. If the game makes side-venturing immersion-breaking, that's a factor to be considered in assessing the game overall... no? Of course, it is. "It's got a great central narrative, but woe be to those attempting side-questing because that's pretty broken as such." See, I had to address the general failures of your argument first... Forgive me for also addressing the "anti-completionist" line I've also heard articulated on this thread...
As to how the devs dropped the ball on side-quests in DAI, I've already mentioned a number of ways. You ignored them to argue generalities, so I'll list them specifically for easier one-off replies on your part:
1. Striking lack of cutscenes
2. Striking lack of dialog beyond text of "I'm in a pickle, do this one thing to get me pickle-extraction?" and "Thanks for the pickle-extraction" upon return. This is bare-bones quest construction mechanics. It's where the derogatory (it is derogatory, mind you) term "fetch quests" comes from.
3. Irrelevance of quests to game's main themes. (This one can partially slide in the sense that it is possible to make an irrelevant quest... say, the Lord Woolsley quest... that's genuinely amusing without having any bearing on anything other than the humor of it. Even 4th-wall breaking can remain game-immersive...)
4. Lack of intellectual, philosophical, or imaginative challenge employed within side-content. You do or do not. That's usually it.
5. Preponderance of non-speaking bosses at the end of side-quests that have bosses. Bosses are all impersonal. (Most side-content doesn't even have bosses, but... Or bosses that may speak a line or two (usually inaudible in the heat of battle noises) but never actually interact with the party.)
6. Preponderance of side-content that is purely visual.
7. Preponderance of side-content that relies upon codex entry reading rather than "real-time" experience. (This one is only partially (mostly) egregious. There are a few instances in which this is sorta cool as a mechanic. The pictures of areas that you use to find hidden treasure used codex entries and worked OK as such (but in that case searching those bloody codex entries should've been easier). Like this one that was pretty cool, matching a picture to actual scenery:)

8. The quality of being a 2nd (or 3rd) tier of relevant quests below the main quests. Investment was clearly diverted heavily into main/companion quests, lightly into most side quests/venturing. There should be no distinction. Experience involving the player should always be valuable/meaningful/top quality.
9. Preponderance of exploration that involves nothing other than traversing terrain and removing Fog of War from the map.
10. Incentivized resource farming
11. Incentivized respawn grinding
12. Lack of consequences for decisions made. (Few decisions were afforded the player during side-quests, of course, so this hardly applies for that reason, but, say, in "The Loss of a Friend" you can either send the demon to go rampaging through the land after Hakkon or kill the demon... same either way other than a free rune for killing the demon and possible minor rep boosts/loss with various companions.)
13. Preponderance of quests that end in nothing other than a simple battle or item... i.e., no different from a typical respawn encounter rather than a character building experience, for instance.
(Always good to end on lucky number 13.) These are all measurable, no? I'm right or I'm not. Make the assessment and see that I'm right. No opinion to be had in any of it. That's what goes on during most of your time in DAI. Obviously no one's made a full-out measurement. No one will. So you could say it's a matter of opinion how much all of that applies. But THAT it applies is incontrovertible. That it applies extensively is as clear as it was the lackluster modus operendi by which they created the side-content. But you'd have to be... surprise, surprise... very intellectually dishonest to pretend that all that is an insignificant portion of the side-content in DAI. It's all that the side-content entails... with some nice, ineffectual offshoots here and there like, as I also mentioned, in JoH or Descent. But, OK, I'll let you as an "audience" assess your "attitudes and tastes" in estimating accurately the same reality I've been slogging through in DAI for 700+hrs...