Those requirements are there for the people who try putting just their name or "...

rmc on Aug 11, 2011 | parent | context | favorite | on: Xkcd Password Generator

Those requirements are there for the people who try putting just their name or "password" or their 4 digit ATM PIN as their password. For very short passwords, only having alphabetical (not even alphanumeric) passwords is terrible. Those requirements are there to prevent some really stupid passwords.