My gut feel is that "rogue root CAs" need to have the fear of having their entire business shut down if they're caught out acting badly, and that CNNIC is the ideal opportunity for US-centric technology companies to take a stand without treading on too many profitable toes. If Microsoft and Apple joined in solidarity and announce they're taking CNNIC out of trusted roots (and, to a lesser extent, Mozilla), then it will be clear that the threats to CA's business/profit have some teeth.
If they let this slide - it'll pretty much be open season for root trusted MITM certs to anyone with a few kilo or mega bucks to spare. It won't stop state-level actors from doing state-level bad-stuff(tm), but it might at least stop them from selling that ability to random big-corps as well.
(And surely the opportunity to stand up to the Chinese Government with broad internet-community backing, especially in the face of the recent Github DDOS - the timing is about as perfect as it's ever likely to get, right?)