There's a problem that people when faced with a dialogue box asking them for a password will be unable to think of a strong password, but that's solved by giving them some form of auto generation.
Writing passwords down is not a security problem, if the slip of paper is kept safely.
One thing to remember about these rules is that there are some other ones not publicized. All you know when it refuses to take your password is that it says "password doesn't match" instead of "password doesn't meet the rules." I got some different error message when I tried using Russian obscenities, but I forget that error message.
Most web browsers now have built-in password managers. Here's to hoping that loop is soon closed with password generation!