That seems kind of like putting all your eggs in one basket. I think the separation of powers is good, even if what it has produced right now is a bad situation.
Mozilla, Microsoft and Google are carrying the baskets. What you have now is N ways of getting compromised, because even the CAs you don't trust can issue certificates for your domains. To be honest, I'm being a bit tongue-in-cheek. I don't think Mozilla should really do this. I just think people should question this naive belief that the CA industry is out there to help the little guy paying ~$20 for a certificate for their blog or forum.