This particular example of script kiddieism is now, fortunately, practically useless, since most systems can now be enabled to use shadow passwords, a system in which the encrypted passwords are stored not in the /etc/passwd file, but rather in a file named /etc/shadow, which can be viewed only by the root user.
However, script kiddies can try extrememly obvious passwords such as password, secret, etc, by simply attempting to log in with the username and password being tried. Therefore, password crackers are still useful for sysadmins who want to ensure that their users are using secure passwords.