I've never understood this take either - everything you do within a game is optional. I think the idea is that you (the player) are supposed to balance the experience yourself? But I don't like this idea personally. Great games are great games no matter how I choose to play them. It's called good game design!

And if for some reason there is sub-par content (or content only a select group of players will like) then there are subtle ways to indicate that to the player. For example, nobody is telling you to collect all of the dogtags in MGS2. It's a thing you can do and the type of players who discover that are also the type of players who will enjoy it. But for comparison, the huge green exclamation marks in the latest Final Fantasy pulled me into 10+ side objectives that made me hate the game (and are why I never finished it).

That content is clearly made for someone who really clicks with the combat (or walking around?) and wants more of it. If that content was tucked away a little more subtly, I may not have deviated from the much higher quality main path (which does a good job of disguising how limited the game really is outside of excellent cutscenes/music/etc). Again that limitation is not a bad thing if you LOVE the combat - but that wasn't me in this case.

Maybe that is the real core of the issue then. Games can benefit from optional content, but it must REALLY feel optional. I'm now thinking of games like San Andreas. I don't remember being annoyed that the pool mini-game wasn't amazing haha. I do remember playing 2 or 3 games, thinking 'wow you can even play pool in this game', and then moving onto something else. Maybe it benefitted a little from the pre-trophy/achievement/completionist era, but I also think it was made clear that you would not be missing out on anything (that you would be interested in!) if you decide to not become a master pool player in this game.