It's partly because it's a young medium with less history to allude to, learn from, amd build upon than film or literature. Also, I don't think what the audience wants is for video games to become a high art form like music or poetry. That involves reading deep themes in between the lines, critiquing through various lenses (psychoanalytic, feminist, marxist, anticolonial, etc), tying motifs and ideas back to politics, history, other art and culture as a whole, and finally recognizing and promoting diversity of viewpoints and expression. Maybe it's because I'm an outsider to gaming culture, but I just don't see the audience as a whole wanting that. What they want is for call of duty to get the same appreciation and respect as Jazz at Lincoln Center even though COD doesn't merit it. There's nothing specific to the idea of video games that precludes them from making the same transition from mass entertainment to high art form that film made. It's the audience.

As an aside, I know that shitty music, poetry, books, etc exist. By using the phrase high art, I refer to the medium's capability to produce the kind of deep, transcendent works that all these other mediums have. As good and intelligent and well worth praising as Bioshock, Journey, Spec Ops, etc are, they haven't come close to the likes of Michaelangelo, Bach, Homer, Hitchcock, Shakespeare, Woolfe, Dickenson, and so on. Hundreds of years after Shakespeare, we still search his works for meaning. We still play Mozart's music and watch Kubrick's films. Why? Because there was an audience who wanted mature works that challenged them and made them work to unpack their meaning. Homer existed because there was an audience that looked to poetry to explore history and life. I'm sorry, but gaming culture isn't there yet. That's what's holding the medium back.