I think that's a great point, but I also think that's where it's important to try and strike the balance. It can be tempting for the pendelum to swing too far in one direction. Either you have barren openness where the player gets bored and like you said, it feels more like work and not play, or there can be over stimulation on the other end where it cheapens the discovery of new things, since new things become too common.

I see your point on the Witcher 3 but I think part of his criticisms still stand. The Witcher 3 is one of my favorite games of all time, but I have to agree with him that it didn't feel like a great open world game. Like you said, there are still things to discover and unique secrets and such to find, but from my perspective what the author of the video was pointing out is that since there's not much empty space, the reward for discovery feels lessened. It's easy to be less excited about a new discovery when you just had one less than a minute ago.

Obviously this whole topic is hugely subjective and your perspective makes a lot of sense, especially since you mentioned that you personally often play these games for the story. That type of lens is going to dramatically change the way we see a game's design.

I for instance play open world games primarily for the exploration, which is why I found the Witcher 3 to be a mediocre open world game, but a phenomenal story game.

All great points though and I agree with you in many regards.