BioWare is good at providing the illusion of choice. They did it in KotOR, and they're doing it here. We're all playing the same narrative - it's how that narrative plays out that differs. Nothing significantly changed the game story in KotOR, either.
OK fair point. Obviously BW couldn't produce a game where throughout you could completely change the direction that it went in i.e. all roads lead to a certain encounter 2/3 of the way through KOTOR.
EDIT: As it would be too expensive to provide multiple storylines making different events spin off in different directions. END EDIT.
I seem to remember that you could change the game significantly at the end if you went dark-side. I mean things like that.