Well, there is a very good reason for this. We don't actually have access to your old password!
It is important for security reasons that you're the only one who knows the password to your account. When you log in, we can only see if the password is correct or not, not what the password actually is.
If you want, you can always change your password back to what the old one was - as soon as you have gone through the process of obtaining a new one and are logged back in.