I agree and disagree, lol. The Witcher is being made because it was made popular by the Games. It's how 90% of people were exposed to it, so I think serving those expectations makes sense. Any time these TV producers deviate too much from what people liked that made it popular enough for them to even make a show, the show suffers.
While I don't disagree that they can have their own take, these characters- just like any other beloved franchise- are known to people. If you strip the core of those characters, or make them look/behave wildly different, then they cease to be the characters people wanted to watch the show about.
The closer these directors stay to the source material, the better the show. There were changes to Game of Thrones and LotR, but they did do a good job of capturing the essence of what was great about those books. Legend of the Seeker pissed off a lot of the book fans because they changed too many characters/concepts.
It's obviously too early to call on this one- I just hope they don't jack it up and make it generic fantasy. CDPR's take was so successful because they weren't generic fantasy. Need more info. A lot is going to hinge on how they portray the world and it's characters.