Yeah, that is true. But that was due to what that particular story was doing. Now that they've done Shepherd/Shepard's story, who needed to be a human, I think the next batch of games would do well to expand the character selection. The universe is too rich in Mass Effect for it all to be contained to a single perspective. At least that's how I see it. And as far as the protagonist being a blank slate, for me that's just the trade off for having such robust customization. It would be nice if the backstory was more concrete but I find that the personality and depth comes through due to the actual gameplay, i.e. the choices you make. The character's a true avatar in that sense; more a representation of the player than anything else.