First, they note that few people have problems with different outcomes given equality of opportunity. This is mostly true: we think of our games as a meritocracy, where skill and/or time invested will yield results. The equality is not perfect, and we hear more from the dissatisfied. “I play rock. Nerf paper. Scissors is fine.” We prefer that games favor the exact balance of skill and time that we bring to the table, and it is always easy to think that The Other is being favored unfairly. Many people question whether opportunities can ever be equal when lawyers play alongside college students: different people start the game with differing amounts of time and money.
I like the discussion of the artisan economy. In real life, specialization and division of labor are the drivers of productivity and prosperity. That is book one, chapter one, sentence one of Adam Smith. Our in-game worlds are often structured such that an individual can do everything, and the transaction costs of trade are greater than the benefits of specialization. We like being able to do everything ourselves, and we are not alienated from our labor when we can start with ore and end with a sword. Or when we start with a sword and end with a shinier loot sword.
Linking the two, we work as we wish and yield gains accordingly. Farm for gold when you need it, use the auction house as you will, play an alt today and raid tomorrow: the system is designed to let you exercise your options, rather than constraining you to a single path. That could cause interesting effects on jobs and careers if new workers expect that flexibility. We already have a younger generation that more quickly changes jobs and expects rewards and fulfillment.
Finally, we want to earn things. We get no satisfaction from having something given to us, and we would quickly get bored with a “game” of picking up gold pieces off the ground.