I started with Conan OGL 1st edition, the extremely flawed book before the Atlantean Edition appeared. I mailed in to Mongoose to get the Atlantean Edition through the special deal they had made to do so. So you can see, I have been with the game since its very beginning.
CPI I think made it plain as day. That they thought the switch to Runequest was a massive disservice to the fans who already plunked down a couple of thousand US dollars for the OGL Conan books. That they would be essentially left flailing in the dust.
Also, the leather cover issue. Matt didn't mention whether Conan OGL would be getting a leatherbound rulebook, or only if that would have been Runequest. If it were Runequest only, it would have been a pretty big middle finger by Mongoose to the people who have supported this game line through two editions.
Fact is: If Conan was switching to Runequest exclusively, the game line would lose me as a customer. As I have no interest in Runequest at all. Same issue with Babylon 5 and Judge Dredd going to Traveller. I like the properties but loathe Traveller. Instant lost customer.
Runequest (and Traveller for that matter) has always been a niche game. It hasn't sold anywhere near as widely as OGL games have. And being a niche game means that support of it would bring quite a bit less of a profit margin to Mongoose and CPI. And yes, that's a serious concern for a company like CPI. A simple matter if, on the business level, it would be worth CPI's time and resources to allow to exist.
Also thrown into this is the fact that the person in charge at CPI actually worked for Chaosium, and saw for a fact how much commercial viability for that company Runequest actually had to the very company who originally created it.