It's a complex matter when it comes to The Witcher - Geralt's supposed to be a century year old swordmaster so the idea of him having to develop over and over with every new title would be odd but obviously development in mechanics is a norm' so the development of stats doesn't work in the context of him.
I play a lot of P&P so I am not opposed to specialising and making a character for a purpose then developing them, but the character you RP in this game is already of a static vocation and with a past and aspirations that may not be in line with the player, it's an odd situation that happens very little in RPG's.
Rather than the player specifying how their character would go about solving an issue he already has a set skillset which lends to the supporting characters chipping in with whichever skills they might have.
Stats, numbers and customisation are cool and all, but they're not everything, the role you're playing is pre-determined, for better or worse.
Correct. Geralt is old and wise, not to mention skilled, and yet he always finds drowners/mercenaries/you-name-it stronger than him

"Stats" are there as a vehicle to provide character customization and development, and since they make no sense for Geralt we can only assume they only slightly modify his
current (campaign wise) interests or focus. That is, even though he is a legendary witcher, lately he has been working extra hard on his swordsmanship/magic/alchemy and therefore it would be natural for it to reflect in his world view and interactions. Imagine if you want to buy a phone/video card/car, then you read everything there is to know and for a few days/weeks/months you're the local expert. Then both you and the market move on.
The biggest problem with assuming that because Geralt is already who he is, "the role we play is pre-determined" and therefore very little choice in dialogue and interactions is OK, is that it makes such an "RPG" almost indistinguishable from an action/adventure. In the end we always "play roles" in video games, like Batman, Duke Nukem, race car driver, invisible tetromino mover, etc.
My complaint is not about having Geralt become a mage or a thief, but rather how rarely we get to use Geralt's known sense of humor, sarcasm and wit to find alternative approaches to problem solving. With or without "stats", I find it hard to believe book Geralt could only think of two things to say in serious situations. With more options like these, the entire game could almost be approached without "talent trees".
Edit + PS: Anyway, I simply disagree with the idea TW3 is the future of computer RPG's. The future of video games in general? Yeah, I hope so! It's really ambitious and it does everything *well*. It's outstanding and will be remembered and played for a long time. But some of its most remarkable features are not unique or particularly essential to cRPG's
