Rant On: The use of Mary Sue as short hand for "poorly written protagonist" with the undercurrent assumption that "power equal bad writing" needs to die in a fire. Mary Sues as a concept only work when describing fanfictions. It cannot apply to original work and in trying to apply it for such you get any character that is "Strong" in setting people as "is that a Mary Sue?" Stop using it outside of fanfics it doesn't work. Rant off.

The WoL is a cypher and written as such, s/he is a visual for the players to experience the story which is as much game play as the cut scenes.