The number of CAs doesn't matter. The essential flaw in SSL is that once you trust a CA, you trust it for all sites. This is what makes a MITM attack so trivial

The number of CAs doesn't matter. The essential flaw in SSL is that once you trust a CA, you trust it for all sites. This is what makes a MITM attack so trivial for someone who is well positioned in a network, and these appliances just make it that much easier to deploy if you don't have all the skills yourself. Another problem is the sheer conceptual complexity of the system. It wouldn't take much to convince your boss to let you purchase an "SSL proxy" to fight viruses and commercial espionage, when all you really want is to steal all his passwords.