Do you have a reference for that? Was quite shocked by that and searching his site found a couple of sensible articles about security, but nothing about emailing yourself your passwords. May just be that my google-fu isn't good enough.
Presumably that is based on his assumption that once the web app receives an email via https and it is to a gmail user, they don't send the message via email (i.e. it never travels over an insecure channel). It may be a reasonable assumption, but seems a little strange to boast about exactly how secure it is.
Most passwords resets do not mail you the password; they usually mail you a unique URL which you can use to reset the password, which often generates a second mail telling you the password was changed.
That prevents anyone from "sneaking" into your account, even if the can snoop your mail / copy your inbox. You'll see the intrusion, and you'll be unable to log into the service after the password is changed.
Storing the password in plain-text in your inbox has none of that protection.