Ebert vs games-as-art

What was a more interesting question is why Ebert claims games weren't art. He argued that because there was no unified artistic vision possible in a game, it wasn't "art". What he meant was because unlike a novel or film, the game narrative has more than one possible outcome. he also implied that games had no singular artistic vision- there was no "autuer" who guided the game- think Orson Welles directing "Citizen Kane" or Joseph Conrad writing "Heart of Darkness".
But the history of art is full of examples that are accepted as art, and great art, that contradict those criteria. Most movies are the result of the artistic cooperation. Even James Cameron has to accept input from other designers, cinematographers and so on. This kind of cooperation was normal fro the great renaissance painters, who often guided teams of apprentices in actually creating a "Leonardo" a "Raphael"or a "Donatello"(I'm not talking the turtles, here).
Much modern performance art, especially the extreme art of people like Vito Acconci and Chris Burden are based on creating situations (like lying for days under a sheet of glass in a public space) then seeing what happens.
Game designers and more importantly could look at defining "gaminess" as an artistic quality that we need more of, and produce games that are more artistic, as well as influencing artists to be more "game-like" in their production.