Why do people go for pottery classes, watch tv, ride bicycles, run, read books, or otherwise do anything other than work? I don't mean to be antagonistic but I find your question to be flawed in the first place; why do we have to always "generate value"?

Also, what is "the real world"? At this point, considering how massively popular Minecraft is, Minecraft __is__ an extension of the real world at this point. It's very unlikely that we will ever lose Minecraft to history. Commit the worldsave to a repo and that world is as good as the real world.