A question developers can ask themselves before and during the development of a world is: Do we enhance or do we substitute?
As I look at the currently existing game worlds, I can see most developers opting for the latter.
Both worlds created as a substitutes and worlds created as enhancements have their strengths and weaknesses.
A world created as a substitute is easy to create, but it can be inflexible and hard to maintain.
By creating the world as separate of this one, developers juggle with two forces: gravity and anti-gravity.
The gravity is introduced between the two worlds, because the game world does not yet have substance: developers want their money, and the game world was made so that players want to access the game world. This draws the two worlds together.
Then, extensive forces of anti-gravity are introduced to keep the two worlds apart; to preserve the purity/innocence of the game world, because many believe this sheltered purity is what makes a world beautiful and profitable.
The players' access to the game world gets limited, because the players are the soiling factor.
Players begin to relate to the situation with correspondence to the two forces: they develop a love-hate relationship. The two forces grind their identities, and either they succumb to addiction, or they abandon the world they love.
(A sidenote: a properly made game based on addiction can be very profitable.)
A world created as an enhancement acknowledges the baser world it enhances. It stands for another layer of reality.
Such a world can be hard to create and even harder to maintain.
Where a world created as a substitute uses distance and access-limitation as its tools to preserve the identity of the world, a world created as an enhancement uses transformation.
A world created as an enhancement recognizes the energies that sustain it and flow through it, and establishes its presence through unique transformation and balance of these energies.
For the developers, this would mean they would have to work many times as hard to maintain control of the project and their status as creator gods.
The question of balance would not be present only inside the game world, but between the game world and the real world, and also between the game world and other game worlds.
This is practically almost impossible, but developers have another huge force at their disposal, the very same force usually perceived as a soiling factor: the players. The new task would be to figure out how to get players/users do all this work for you (and themselves), and do it well.
For the players, it would feel less of an escape, and more of an extension to regular identity.