I been sayin' that since I got my first NES back in '89. Final Fantasy, Dragon Warrior, Zelda... they weren't games so much as stories. And the trend only continued on, moving out of the RPG realm, into RTS, FPS, and various Sim games.
Take a game like Halo... the latest derivation is actually a prequel, where you play the back story to the original three games. What's more, it's structured as a tragedy, as there is no way to win (the end is already known... the protagonists fail, Reach falls to the invasion), but the appeal is in the story, the details. It's no longer the "what" that is the concern, but the "why", the "how", the "who".
It's a lucrative, and viable option for writers... not only do these games require writing for the games themselves, but also for the novels, the cartoons, the movies, and the web series they spawn.
And as for lit-cred... not long ago the idea of a TV show being accorded the same respect as classic and contemporary literature was the stuff of mad men and fools. A complete nonsense idea.
Things change fast. And increasingly faster.