You assume that open world game should have the same content density as corridor shooter (loosely speaking).
I disagree. Sheer world size in Open World game is feature and selling point. It doesn’t need lots of hand placed content or story or things like that. It needs nice looking, somewhat immersive world, which is dynamic in its nature (it’s actually simulated, not scripted with capture towers…).
To that end, yes Dynamic GI is imporant. It gives you better looking world, which is actually quite important for open world games, where world is playable content on it’s own.
You clearly just don’t like open world games. I do like, I get mad when open world games are trying hard to be like small story driven games, because it’s not where their strenght is, and that’s the reason why there is so much survival sandbox games. Because there is mark for it, and consumers of those games like them not for the story, but for the world and multiplayer.