Yes, the whole password business is a complication that negates the value of the service. I'm not going to hang onto some piece of trash--the plastic wrapper with the label--to retain the password and neither are many others. If you expect people to use a new password with each issue, then stick the label directly to the magazine.
It would be much more convenient just to be able to log in and set a password that expires with the subscription. If you could somehow encode that information into the label, I would be willing to do it once, but it's ridiculous to have to enter a new password with each issue.