OP is discussing the physics, density, and NPC interactions.
A lot of other people here keep bringing up gameplay design and graphics, which are separate things.
An example to help clarify: Elder Scrolls II: Daggerfall looks ancient today and the gameplay of it is average at best, but the world in it felt vast and overwhelming because it felt like everyone had routines and things to do, including random elements like creature appearances, or someone ending up dead by some event hours before you showed up, causing you to have to investigate(if you're curious) simply because you arrived too late.
Bethesda sort of went further and further away from NPC routines and 'missable design' to appeal to the completionists and the casual market, which ended up doing more harm to them than good. Rockstar leaned into it more with Red Dead Redemption 2.