So if I had to guess, it's that they wanted to display more security-related information, which made sense in the developer console but not on the certificate screen. And that viewing the certificate was confusing non-technical web users.
Edit: http://www.herongyang.com/PKI/Chrome-40-HTTPS-Certificate-Ge...
The old screen showed the same information as in the "Security" tab. Right now a click on the "Secure" button in the URL bar doesn't even show the certificate issuer. It is useless this way.
That’s actually not a very good practice. You’ll get http non-www to http www to HTTPs www,for example.
Why is this a requirement for the preload list?