Mr. Vega was on the right track when he said the story elements that make a movie differ greatly from those that make a game. Even the length is quite different -10 hours is a short game yet a very, very long movie. Granted, not all hours of gameplay in a game are dedicated to plot development, but if you look at a game like FreeSpace a significant amount of story elements happen each mission.
I also think those people who mentioned that Hollywood doesn't understand games also had it correct. Games are about far, far more than the action and effects. There has to be other elements in there as well. There has to be something in there that makes the gamer relate to the characters, that make them feel bad when characters die, give them suspense when they're in danger, etc. 99% of movies made from games lack all that. The characters are so poorly thought out and acted that you just don't give a **** about them.
Unfortunately we're starting to see similar trends in both movies and games now. Larger companies *caughEAcaugh* are starting to just throw money at the technology and go for the "wow" effect rather than trying to actually develop an amazing movie or game that actually gets people emotionally involved. Hollywood doesn't understand that gamers actually want to care about the character(s) they're playing, the people or monsters they're fighting, etc. They don't understand that it's about more than shiny explosions.