Carmack is a lot like Steve Wozniak. There's no question that he's an incredible hacker, but (as I've heard second-hand) he isn't crazy about managing large teams. Carmack was his most influential in the late '90s, when a small group of developers could still make AAA titles. That isn't really true anymore, now that high-end games routinely involve a hundred or more developers.
Carmack's team is still large enough to develop a top-notch engine that can be used in AAA titles put together by some other shop. The idTech engines have not been slacking in innovation, and the biggest thing limiting their use outside of id recently (lack of scalability down to low-end hardware) is clearly not a problem anymore.
They're clearly making more of an effort with Rage than they did with previous engines. They were spoiled to a degree by how eagerly 3rd-parties licensed the Doom, Quake, and Quake II engines. Id developed a nasty reputation for dumping code on licensees with little support. In fact, one of the main ways Epic stole the licensed engine market from them was by providing much more aggressive marketing and support. Id's attitude was always "if we build it, they will come".