Every article that mentions a company tying their authentication to Facebook Connect unleashes a horde of people saying "I'm going to cancel my account", or "this is the worst idea for their business ever" ..
Why is having a central authentication system a bad idea? How many times have we seen articles where companies are storing information (password included) in plain text or a weak cipher? How much developer time is wasted rebuilding authentication systems? How much user productivity is lost trying to remember passwords if they use different ones (or lost managing things through a tool like 1password)? How many security breaches are caused because people use the same password across many sites?
Facebook Connect is a good thing. I understand that the data mining and privacy concerns. These concerns aren't real, not because Facebook isn't collecting information but because everyone is collecting information so any privacy you have left is an illusion of privacy, not actual privacy.
This is Wrong. Our privacy is only actually gone when we consciously decide to give it away, or throw our hands up and say "oh well, there's nothing we can do".
Facebook Connect isn't bad in and of itself, and neither is central authentication. But a lot of people understandably don't trust Facebook to manage their identity for them and would prefer to manage it themselves.
It's still perfectly possible to maintain reasonable privacy on the web, and any site or product that doesn't at least give me the option of doing so isn't a site or product I'm interested in using.