'root' is the one known account on your system. There are script kiddies constantly probing systems and attempting to login to the 'root' account. If they succeed, they have access to a privileged account, which is the worse thing that can happen to you.
What is it you think you need to do logged in as 'root'? If we know more, maybe we can suggest ways to not need the root account enabled for login.
From the command line, you can use the 'sudo' command.
sudo command-that-needs-to-be-run-as-root
sudo -s # get a root login prompt
If you are into 'ssh' you can store your personal ssh-keygen keys in the /var/root/.ssh/authorized_keys file and then ssh root@localhost to get a root prompt. Just make sure you protect your ssh-keygen keys.
It is possible to start some GUI programs running as root
sudo /Applications/program-name.app/Contents/MacOS/program-executable-file