I have vivid memory of walking into the HQ of the first DX, it was my first experience of an FPS safe zone/hub area. Something felt very freeing about it, and now in later life I realized that it was being given full agency in a game. No constant combat or objective. From a hub you have the agency and breathing room to wander and explore the world building, and a good immersive sim gives you lots to find and do while you wander.