On the gameplay side of things, we've got games that really try to tell a good story and fall short due to technical details. To some extent, the way games are set up (rules, consequences, and rewards) are sometimes at odds with storytelling. You can't have a slow tension building scene in a game. Whole narrative tools are stripped down or abandoned entirely for video games. This tends to lead to the aforementioned over-written dialogue instead of a more traditional version. It's also directly tied to the massive use of cliche characters in games — the developers don't have as much time to make them and it's more important to convey what the character's about instead of creating compelling arcs.
I’d like to end by saying that I love that video games have attempted to touch deeper subjects. I love how moral dilemmas and the illusion of free will are major themes in many current games. But the medium’s still immature and its attempts are often haphazard, as is the case when pioneering any field. One day video games will have their Watchmen or Citizen Kane and I honestly believe we’ll get it as long as the industry moves away from gimmicks and try to deepen their gaming experience and characters.