I'm instantly skeptical any time I hear people make sweeping generalizations about the lack of high-quality storytelling in videogames. I personally think that 95% of people who play games are only paying minimal attention to the story to begin with (Jeff, I'm not including you in that 95%, I get the feeling you pay far closer attention to story in games than most do). I think many videogame "stories" are fairly well put together.... just as well as the average movie. The problem is that the experience of PLAYING the game often gets in the way of storytelling. Our attention (and therefore our ability to absorb the story) is constantly divided.
Another issue is that the primary focus of most videogames is not storytelling. The primary focus is gamplay, with the story acting as a metaphor or "excuse" for the gameplay that is taking place.
Of course, the ideal situation is to have a game with great storytelling AND great gameplay, but the truth is that for most people, a game doesn't need to have a great story to be enjoyable. On the flip side, a game with great story but bad gameplay just won't be enjoyable for most. Its an issue of priorities, and I feel that storytelling is often not the priority of the developer, or the player.