"When I think of games in digital spaces, we tend to lock them down and apply a very rigid system to them, and I don't think that necessarily needs to apply,"
Best statement in the entire article, imo.
Players want to have the tools to tell their own story.
The tools are those game mechanics that the developer's provide.
Lego and Minecraft have done so well because they provide simple tools for people to express themselves.
From the extensive reading's i've done online to ascertain "what MMO players want" in the hopes of finding the key to a great game that will be designed, minecraft simply proves the point that simplicity and freedom trump all.