One problem is that we still call these passwords. A change to pass phrase implies longer. If I tell a user to pick a password they come back with Fido or Fido1. If I ask for a pass phrase they'll come back with "My dog is Fido." This usually is easier to remember and much longer than a password. Factor in a couple of numbers and you've got a good start to getting you (or your users) using strong passwords(phrases). "My 1st dog is Fido." #, punctionation, cap and small.