Designing content vs. designing the end-user experience are two different things. The same is true for game design teams. There are far too many other variables that affect our overall enjoyment of games for their overall form to be left exclusively in the hands of ludic artifact designers. The fact that players can see through the story to the underlying mechanics does not negate the importance of the fiction. Think movies, where the aim is generally for the camera's many conventions, techniques, and mind-shapings to be invisible and unnoticed by the audience.