Neither users nor browsers could tell whether a site is supposed to run a domain- or identification validated certificate. (Fun fact, HN uses a domain validated cert.) All you get is higher costs for some X.509 fields nobody ever looks at, and nobody would miss if an MITMing attacker replaced your ID validated cert with an domain validated one.
Doesn't protect against a hacked/rogue CA, but against someone getting access to your DNS/mail/web server and getting a useable certificate from a only-domain-validating CA.
But should we? I've never looked at an SSL cert past seeing the green lock icon and "https". Maybe I'm an idiot but I just don't see the value in checking it every time I go to a site AND remembering if it was just domain or one with identity the last time I visited...
LetsEncrypt will be good for all those sites we deploy with self-signed certs, but won't be replacing major sites any time soon.