Here's Ron Edwards's answer, in the last minute or so of this video:
The enjoyment of the medium for the properties that it offers, that no other medium I know does. It really is a valuable human thing to do. Intimacy. Enjoyment. Creativity. Unpredictability. Varying levels of success as you go along, which is OK, right? And the surprising freedom, or at least semi-freedom, the intractability against commerce. It's really hard for commerce to take over, if you're just focusing on enjoying play. That's kind of a nice thing.
The enjoyment of the medium for the properties that it offers, that no other medium I know does. It really is a valuable human thing to do. Intimacy. Enjoyment. Creativity. Unpredictability. Varying levels of success as you go along, which is OK, right? And the surprising freedom, or at least semi-freedom, the intractability against commerce. It's really hard for commerce to take over, if you're just focusing on enjoying play. That's kind of a nice thing.