Admins who impose those rules think they are improving security when in fact they are doing the exact opposite.
In the end, it doesn't really matter. The way "hackers" get passwords is so stupid that it's almost insulting. Remember that Kevin Mitnick guy? He would do retarded shit like wear photocopied badges and physically go inside the building. Have a smoke break and talk with people who work there and go back inside with them. Just like that, all of your security systems have been bypassed. People let him inside the building; no hacked keycard needed.
Some of the more recent big hacks are just as dumb.
call the secretary: "hi, i'm blah blah, can you tell me the name of the network admin?"
call the IT people: "hi, this is (network admin) and I'm doing a test on the system, can you send a reset password to (some email account)"
*they send the reset password*
*log in as that person*
*download all of the hashed passwords then start hacking them*
You want in? Just ask. Lots of people will bend over backwards to help a friendly guy on the phone.
Sometimes this dumb shit is needed. I heard one first hand story where a woman was trying to close her husband's phone account. Why? He died. She tried to tell them that a million times over and they just didn't give a shit. You're dead? Well fuck you; you're now a Bell phone customer until
the end of time (even after you've died!). She had a guy friend call as her husband and close the account. It's just stupid.