I understand your point, but allow me to disagree, as I have given this quite a lot of thought. Like I explained I first met Geralt as an amnesiac, I have since played both games numerous times, I know everything the RED's have said about him & his world. I also know quite a bit beyond that as an unavoidable consequence of reading & engaging here in the forums. I feel I know more than enough to approach TW3 and see how the RED's deliver these new characters that are so important to Geralt, yet have hardly been referenced in the game, a difficult task.
If they manage to introduce us (those with no prior knowledge of the characters you mention from the books) with the same skill that they introduced Geralt & friends to us before it will be an incredible accomplishment, and one I wish to experience with my slate as blank as possible. Only then will I be able to truly say what an epic game trilogy The Witcher is. And maybe that's the simplest point I can make to you, I wish it to remain a game trilogy for me until it is complete, not a book -> game translation.
I understand and respect your decision, everyone should enjoy this amazing series the way they want to I agree with you in that the games should be able to stand alone without the books, and that you'll be able to better judge the quality of the game's story (or admire the skills of the REDs) by seeing how well Witcher 3 introduces new characters from the books. CD Projekt has handled it really well so far with Geralt's amnesiac condition. It allows players to discover things about the Witcher along with Geralt himself.
I can also see how playing the games first could be a really interesting experience. One of the things I loved about the Witcher 1 when I first played it was how foreign/unique everything felt (this was before I had read the books). I can see how having too much backstory can take that feeling away.