I've been thinking about that actually. The choice of either giving a well developed character for the player to control, or letting the player create his own character who will then be forced into the predetermined plot. Geralt I feel works well in The Witcher, he adds interest to the game. It might be easier for me to feel like I literally AM the protagonist if it was a character I've created to suit me, but then you'd lose the charm that comes with Geralt. The choice would also affect how the game is designed in some sections with regard to player choices / freedoms.
Different options work for different games/plots though. Maybe this game will designed to for user created protagonists.
What can change the nature of a man?