I think when you have two very dissimilar methods of delivery; W2 being a very linear and focused story to W3 where the game is not as linear and not as focused. I think they both have their merits. For W2 it gave players many interesting and full characters to interact with yet it also managed to very poorly convey the surrounding world and at times it seemed even myopic because the main quest was the only quest. In W3 there are as many interesting and full characters but they are spread out and given in moderation, clearly it works to diminish these some aspects in some regards, but I think the benefits that came with this new design are actually superior in many ways, which I will try to detail.
- Even though W2 story was intense I don't feel the same replay-ability from W3. W3 allows the player to not only take their pace, but it does a wonderful job of conveying an outside world. If we try to go past the scaling of the world and imagine it properly then Geralt is on a quest that take a long time to complete, simply to get from Crow's Perch to Novigrad takes a lot of time. Geralt's zigzagging through the world invariably means that he is also living the life of a Witcher and that he has secondary concerns to attend to. Sometimes you need to meddle or find yourself facing mundane problems and W3 allows you to immerse yourself further into the world in this way. Granted it might not be the most exiting when you finish it for the first time, but as you replay the game more than once this sort of pacing and player choice allows the player to explore and settle into the world in more ways than a spicy and intense story campaign could ever allow for. This grants the game staying power that can endure for a long time.
- I feel that the characters in W3 are just as enticing and interesting and manifold as its predecessor, however it also is not something that is spoon fed. Going back to long term staying power, I think there is a certain satisfaction to playing or reading something for the 3rd or 4th time and finding something new that you missed in a previous play through. This might come from overhearing a conversation that you never had heard before, or finding some piece of clue that you overlooked, or find new paths in the main quest from doing things in a completely different order, and etc,. These things can change outcomes in a subtly satisfying ways or present new information that can change your perspective on a character or event. Diluting the content into the world can make exploring and playing through the game differently actually rewarding. I know some people think that the exploration part of the game is finding the hidden treasure chests, but really that is quite a shallow way of looking at it. Exploring the game doesn't have to be the literal interpretation and act of going into the abandoned wildernesses of the game, there is also exploring the game in places that you have already been to and finding the things that you missed before. This probably means less for those who insist on completing everything on the first play through via the aid of guides and walk-throughs; I really think that playing and approaching a game like this in such a manner will only work to remarkably diminish the game.
- I do agree that there are certain characters that might seem to act nonsensically and have dissatisfying interactions or conclusions. There were some characters for instance, from the top of my head, Djikstra, that I actually thought and agreed with regarding the community's verdict. Yet on my second play through I found that the way things unfolded and transpired actually did seem the most reasonable based on what you can glean in conversation and uncover independently. I'm not going to go into detail into why because it would take delving into and analyzing conversation and other miscellaneous things, suffice it to say I found that the game did include more than enough compelling and satisfactory content to justify that certain unfolding of events as the most rational outcome. I think this is the reason why sometimes it might seem like this game lacks the depth of W2 story (despite being somewhat complex the information was quite transparent and available, and even repeated many times over), it's because the mechanisms which deliver the depth are more subtle and require more than just the quick scan reading. There is lots of information, you just have to work for it. I'm not calling people out on being lazy, all I'm saying is that the explanations for many things in W3 are not always made apparent and obvious by supporting characters or narrative. Again I think this adds longevity to the game and will ensure that players encounter something new or unexpected every time they choose to play it again.
- W3 is more about delivering story with emotional pertinence rather than novel and creative story telling. Just because a format is heavily used does not mean its worth less than something new or creative. I think it would be quite facetious to state that the W3 does not engage you morally, or even emotionally at times, in its quests. Many, if not most, side quests certainly manage to to do the former and some even the latter. In W2 there was basically the main quest and that was it. I find myself hard pressed to think of another game that has managed to engage the player as consistently through as many side quests, small or big, as the W3.
Now I'm not saying that W3 method of story telling, plot development, or actual plot are clearly superior to W2. What I'm saying is that W3 has many merits in this regards which can be easily overlooked, especially in a short term evaluation.
As for the actual deconstruction of the plot into the player performing mainly favors for favors and locating characters to find some other character, I actually find quite amusing. It's possible to deconstruct practically everything into the carrot-on-the-stick metaphor, even your very own real existence. This is a very trite way of criticizing anything, especially when it comes to things like works of fiction. Personally I used to do this quite a lot, but one day I decided to stop. The reason was simple, I was actually diminishing and, even to an extent, ruining things that would (e.g, movies, books, games), or should, have been otherwise enjoyable experiences. When you deconstruct the plot as such you actually work towards shattering the illusion that you dearly want to partake of. When the extant content, regardless of how good it is, is rendered to its bones, particularly for things like fictional works I would dare say that in every case you will manage to devalue it.
So in conclusion I think I stand on the other end in regards to the OP. Despite the fact that the plot is not overly creative, it still manages to be engaging. More than any other Witcher game you really see Geralt display a wide range of emotions, reactions, and humor. I cannot remember the last game that I played that had such a compelling protagonist (especially since in the first two games I found Geralt somewhat flat). W3 made Geralt my favorite character, and to me that was something special because very rarely do I ever find myself in a game of this genre and think that the protagonist (which for the most part is a vessel of the most average person possible) is my favorite.
As such it is a difference in opinion and perspective, yet I still find it somewhat irritable to accept that this game's story was uninspired and disappointing as a deliberate and not impetuous opinion. No game is perfect. W3 has many flaws. The story has flaws, and even then the things it does right and those moments when the delivery is exceptional the game really shines by giving you a very memorable experience. Well that, or perhaps my standards are very low...