when setting up a new user account or install of ubuntu the user should be warned but not stopped if they try to set a simple password. EG less than 6 characters, contains all letters or all numbers, is on a common password black list or has lots of repeatition.
This would strengthen the system sufficatly and be easy to implement.
please don't, if I was a newbie decided to give linux a try by ubuntu and must build a alien password I just give up after the third attempt or just format the HD when I forgot the password. the people who needs strong passwords know this, don't make the life harder for my "grandmother" :D.