Do you have an alternative hypothesis? Because I've heard the "they canceled the novels because WotC secretely hates Ed Greenwood!" theory, and let me say that's extremely dubious.
They canceled the novels because someone at WotC up and decided they weren't a novel company so they decided to externalities it by getting another company to do it, but failed specularily. The only reason reason RAS still does Drizzt novels is he worked his ass off trying to make a deal happen with a 3rd party company.
Honestly it's been a disaster both MtG and D&D side, story used to be at the heart of both and externaliting the novels killed that.