I don't really agree with your contention that the Behemoth quest was not as well-structured as a Witcher 3 larger side quest. One thing you should remember is that you are dropped into the middle of the quest, and didn't experience the start of the quest (you were only told about it). Besides that, the hunt for Behemoth was better than most monster hunts in the witcher in my opinion, since it requires you to take a large intermediate step in order to beat behemoth, making it more than a straightforward confrontation.
I personally spend around 6 hours in Duscae, though most time was checking out the battle system and doing some leveling.
To be clear, I was commenting on how it was presented explicitly in Episode Duscae. Also I never said I had any problems with the structure. I had an issue with the lack of context and character development(story).
In a Witcher 3 hunt, the hunt itself is just the setting. The real story comes from the context added by the characters wrapped up in the quest. Typically the context comes in the form of an entire story arc.
For better or worse, the Episode Duscae quest focused on the moment to moment of the hunt, and didn't attempt to add meaningful context beyond "car's broke, let's get money". Where as a more interesting subplot may have revolved around Prompto struggling with his own self confidence as a member of the group as a result of him apparently busting the car, and as the quest goes on maybe he begins to see where he fits into the group and ultimately finds a new resolve to try to be a better teammate/friend. Or take your pick of any other character or set of characters and make it about them. Brotherhood is doing quite well with that style of storytelling.
To be fair, Duscae was a preview. Implementing that kind of context requires the creation of a lot of content that was probably out of the scope of that demo's budget. These types of stories may be very common in FFXV. That said, the lack of context in the demo as it was delivered left the experience feeling a bit dry. If it wasn't representative of the average writing level they shoot for in a quest of that caliber in the final game, great. If that quest really would've had a lot more payoff if we had only seen what lead up to it, or what came right after, great. That being said, the demo released as it was, and unfortunately the lack of context(in this demo and their entire marketing campaign so far) is probably why even to this day a lot of people don't "get" FFXV.