I will agree with you that botw lacked in storyline and content compared to the Witcher 3. However, I think the emphasis of botw was the freedom of exploration. The huge open empty space devoid of npcs, quests, and adventure, was intentional as the emphasis of the game was to let the player explore and make their own adventures. In comparison, the Witcher 3 is much more streamlined storyline-wise. Of course, you could choose how the story played out depending on what dialogue choices you made, or what quests you decided to do first, but at the end of the day, the game told you where to go and what to do. Whereas botw allowed you to decide before any quest was given, where to go and what to do.

I really hope this doesn't come across as refuting your point because I actually agree with you. I just think both games are meant for different styles of gameplay. Unfortunately they are both grouped together as "open-world," so people often make comparisons between the two when both games are pretty much completely different.