And how many players even know what that reason is? I've read the books, and honestly, I can't remember - unless it was just that Geralt has white hair, a reputation and is from the Wolf school.yeah, the best thing about this game is how immersive it is, they call you white wolf or gwynbleidd for a reason, a custom char wouldnt give you the same depth in the story as a default char would
Still, just to play the devil's advocate for a bit, the same thing can be said for other games: Dragonborn is called Dragonborn for a reason, Warden is called Warden for a reason, Watcher is called Watcher for a reason etc. In all these examples that reason is, in fact, even more relevant than in the case of the White Wolf.
Some games have a predefined protagonist, some have one that you create yourself. They both have their pros and cons, and I have no symphaty for fools (not referring to you) who claim that one is somehow inherently superior to the other. I think it'd be fun to see what CDPR could do with the latter after having created three games around Geralt.