If that were the case all these stories would still matter and be relevant BUT we could play OUR Witcher male OR female who sought Geralt for some specific purpose, wouldn't really matter.
All Witchers are male. There are no female witchers in the fiction.
Then we wouldn't be forced to play a predetermined character whom already has a personality set in stone, where we are given the illusion we are making decisions.
There are no illusions of making decisions. You are making decisions that affect the plot. Did you see how in the movie the female with the red hair Triss and the dwarf Zoltan tell the story of Geralt escaping from the dungeon differently and it plays out in the video? That's not an illusion.