I wouldn’t want official images in my games because I prefer my readers being able to imagine both the setting and the characters as they like. I don’t need or want a canonical visual expression of my story; in fantasy, especially, I think words can evoke richer mental images than most artists could manage to capture.
It’s also worth noting that there’s a vocal fan contingent who HATE images, who’ve been out in force since character drawings started regularly showing up in CoG titles. Some of them just have gripes with the style, but many feel it’s a betrayal of the medium – that a CoG game must leave everything to the “vast, unstoppable power of your imagination.”