I disagree. Let's take life as an example. Do you know about what happened in the world before you were born? How? Did you go through a prequel to your life? No, you know what happened through story telling. We don't need to play through things to understand the story, it just needs to be relayed to us at appropriate times. I agree the story has been lacking. Not to the extent you portray but alot could have been done better without the need to go outside game. The elder scrolls do this well through in game books and such. If you want to find out things it's there in game for you, if not then just kill things. As far as motivation for killing stuff, they shot me first. Plus, ugly ass aliens, enough said.