Distance is measured in time, not space.
That's not literally true, of course. But it does seem to map to how we think of distance. I live half an hour from work. The grocery store is a 5 minute walk away. The big city is four hours away.
So when you apply this to virtual worlds, geography needs to take into account travel time. Uldum is right next to Stormwind, despite being on another continent. This is because the portal is there. The portal is a convenience, but it also makes the world seem less like a world. Without the portal, the game would be more inconvenient.
I was reading the debates between theme parks and sandboxes, and it occurred to me that inconvenience is a very important factor in making the virtual world behave like the real world.
Take the entire concept of trade, for example. At one level, you buy items where they are cheap, transport them to where they are expensive, and sell them for a profit. But this entire transaction works because of inconveniences. Resources are distributed unevenly. The markets in the two different areas are not connected. There is a limit to how much weight one can carry. The transit takes time. The transit might be dangerous.
There are a lot of elements in a modern MMO that would need to be stripped away to model this type of trade. No common auction house, weight restrictions, and a long travel time to get from area to area.
The theme park MMOs are all moving towards smoothing away as many inconveniences as they can. And the playerbase demands it. Look at the outcry when portals were removed from Dalaran.
And yet, for sandboxes to truly work, I think they won't work despite inconveniences, they work because of those inconveniences.
But inconvenience is, well, inconvenient. Maybe sandboxes can never work, because the required inconvenience to truly simulate a virtual world will just drive players away.