Pretty good list, apart from Mass Effect. I mean you could do something unrelated to the main storyline, but the idea of having anything related to the main storyline is doomed to fail. Since all the fans of the series have there own vision of how the story should really go (that's the main idea of the game) and making a movie, where you can't do anything about the stupid things Shep is doing on screen.
My nightmare scenario would be something like this (May contain spoilers from the ME series): Shepard goes total paragon, apart from being a horrible racist, leaves Kaidan Alenko alive, kills Wrex and helps out the council in the finishing scene. And then in ME2 he/she only chills out with Jack and Zaeed and kills everyone else. And someone else will think this is the best way to play the game.