The original ending of Neon Genesis: Evangelion featured Shinji in a void of infinite potential. His first act was to restrict himself, because he needed ground to stand upon and a sense of “up” and “down” to orient himself.
Players enter a virtual world of infinite potential, and their first question is “how do I kill things?” The second is “how do I get stuff?” MMOs are in a feedback loop with those impulses, designing around an endless cycle of killing things to get stuff to help you kill things.
Second Life and MineCraft are more open-ended than Yet Another Fantasy Theme Park MMORPG, but people exhibit the same behavior. Given a realm of potentially infinite space, we immediately want homes, buildings, a farm. Virtual glory comes from your castle, when you could be free of all that. We have left terrestrial space but brought a hunger for the dirt with us.
Everything you own in-game is a database entry, with only the significance we assign to it. One of the most fundamental violations of the game would be to edit that database directly. It would be against the rules, immoral, a trivialization of all the work everyone has done to get their legitimate database entries.
Because virtue lies in accummulating database entries that translate into virtual property through the execution of virtual violence.