I think there was a request for comment previously and the outcome was that enforcing any password strength is bad, instead a warning should be shown. Perhaps Requests for comment/Passwords is a part of that discussion, it may have happened at more than one place however.
A quote from that page is "We can encourage stronger passwords without requiring them."
I think this may be worth implementing, perhaps as
- an e-mail to privileged users whose password is weak, and
- a warning ui for people who are signing up.