"Writing a good story is hard. Making a good video game is hard. Trying to make a good video game that also tells a good story is damned near impossible.
Not that they don't try. Video game makers are working hard to achieve their dream of a playable movie, or at least a game that looks like a movie in a two-minute trailer. But when you're playing the games, that "I'm in the movie! Whee!" illusion disappears as soon as you hear things like..."