I've only read a handful of genuine game novels; probably not more than two dozen in my entire life, and none in the last ten years or so. In my experience, they are rarely better than mediocre fare. And sadly, many are actively and aggressively horrible (Rose Estes, I'm looking at you.)
I think calling Lovecraft or Moorcock "RPG related" authors is at best counter intuitive, at worst completely nonsensical. I've read a fair amount of both (especially Lovecraft, I dislike Moorcock) but not in relation to any RPG. And as fusangite says, I actually don't even read that much fantasy anymore at all; RPG-related or not. For that matter, I don't read that much fiction anymore, but if I do, it's as likely to be a mystery, thriller, or historical fiction than fantasy related. Probably moreso, as a matter of fact.