Isn't that the situation we are in now? All it takes is one CA with poor security coughDiginotarcough and the whole system is broken. I'm obviously ignoring the fact we have CRLs - but if someone has a signed cert for say chase.com or google.com they can do a lot of damage in a very little amount of time.
Maybe I'm just cynical that there is a profit motive to CAs. I mean, you can't tell me that it's just greed that you can purchase a certificate to turn a user's address bar green because it's "extended validated". The average user won't notice, or even know what that means. Big picture behavior - there is no functional difference between a EV and non-EV signed certificates.
My opinion: if we keep the SSL/CA system the way it is today - we need fewer CAs but create non-profit CAs where the average person can get CA signed/trusted certificate for free or next to free. I'm not talking about grabbing some random dude off the street and start a non-profit - it should be funded and sponsored by companies like Google/Verisign/Microsoft etc.