Read the description again. We will see the story of Hawke through the eyes of the character, whereas the myth around Hawke is already defined and independent from the narration in the game. Playing DA2 you will develop your real Hawke.
Everything else will likely build upon the myth if directly referred to and not dependant on a savegame, whereas the players in later games might see the real Hawke shine through somewhere.
So is Hawke an important character, or is he incosequential compared to the events surrounding him?
If he's important, does that not mean there'll be a "canon Hawke" - most likely a white male warrior, with shaggy hair and five o' clock shadow? If that's the case, why bother pretending he's anything else? If he's not important, why must his/her name be Hawke? Why must s/he be a human?
Really, I'm not sure what my complaint is, here. It just seems odd to offer so much freedom in a previous game, only to snatch it all away in the sequel. Granted, one's origin really only effected the first couple hours of the game, but there was still that
illusion of freedom, even if it wasn't really there.
There have been many great games with fixed MCs - this could end up becoming one. Still, it just leaves me uneasy.