Allow me to disagree here. Objectivity must be based on "hard" facts. Numbers are great for this. One number could be dates and which came out first, so in that case you would be correct. However, if you consider the number of people who played the games and never read the books and viceversa, then it is clear for most people the Witcher series is a "gaming" franchise.
That is not a good argument. The downfall of our society is already happening.
Books are getting niche. A book will almost NEVER even COME CLOSE to a video game right now.
It is a SAD fact. But a fact nonetheless. A writer, even if he/she were divine, cant equal to a video game or a movie in 2015. They just cant.
And that is bad.
As for popularity... I dont like that. Do you know how tiny Witcher is compared to some games out there?
World of Tanks has more players playing at this moment than Witcher 1 and Witcher 2 sold combined in a few years. Wargaming can buy CDPR and the franchise and probably recoup the cost in a week...
And there are (only very few) companies even bigger than them.
RPGs are a small niche genre when compared to the big picture that is gaming. Witcher is not even top dog in its small pond. Popularity is not what we as a community should consider to be something given....