I'm surprised by the amount of negative comments. Independently of what do you think about HTTPS and CAs in general. Given there the alternative currently is plain text, I'm actually surprised that it wasn't a signal before.
* Certificates are expensive (to buy _and_ to manage)
* Crypto is hard and there will be a lot of screw up with inadequate certs in the wild for a long time. Just having a certificate does not mean much if it weak or broken.
* Can't help the feeling it's an indirect push for cloud business hence possibly eating the margin of freelancers / ISV
* Security Theatre : a lot of critical information for business still transit by email. Will Google force encrypted emails for the greater good ? I don't think so.