I have to say that I was hugely impressed with the Escapist's threads discussing the plot of The Last of Us.
http://www.escapistmagazine.com/forums/read/9.819183-The-Last-of-Us-Plot-Ending-Discussion
This thread wasn't about how great the gameplay was or what texture resolution the graphics were, it's about the characters of the main protagonists, and how well their choices at the end of the game reflect the characters they've established over the game, and why the seemingly bad, immoral, or questionable choices were justified in their minds.
It's as in-depth as any book or film discussion will ever be on their artistic themes, and we also had these same discussions on the themes in Bioshock Infinite, and Spec Ops the Line.
These forum threads prove exclusively that videogames have reached their potential as artforms to make the player think about their own actions that they took and how it reflects on them, as well as the actions of other characters and how their beliefs, needs, and struggle to survive shape their choices and actions.
Gaming has reached its potential to be as artful as any movie or book can be, but Spielberg and Lucas couldn't actually know this unless they actually were to take an interest in the medium and play these recent games, instead of what they have most likely done, which is base their opinion on the TV advertisements of COD and Battlefield, and Fox news broadcasts of the latest moral outcry from the last disaster-in-close-proximity-to-a-videogame scenario.