Billy: A little more info. Logging into x as root is never really a good idea and many distros that do use a root user for admin tasks disable root login in gdm/kdm. Logging into a text session as root or getting root from inside a user's session is a completely different story. Getting root with su instead of using sudo makes life easier on multi-user systems where the user that is logged in isn't trusted with sudo access and has been disabled in the sudoers file. There is a way around that but it is a bit convoluted. On a ubuntuesque system like mint where launching an admin function from within x asks for a sudo password anyway, the root user is even less useful. This is one reason that so many hardcore old-school linux users prefer the old fashioned root user to do all admin tasks instead of the sudo system; as an administrator you can walk up to a user's machine and gain the power of god easily using your root password and the poor user can't do any admin tasks without you. (And we all know how some sys admins thrive on their delusions of grandeur in the office don't we?
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There are other minor reasons but I won't go into that. Let's just say that on a single user system or when all users have sudo authority, having a root user has very few advantages. Linux is styled after Unix which was designed for multiuser environments where users don't get root access. A home pc is different kettle of fish.
In most cases if you want to do a lot of admin tasks consecutively, issuing something like "sudo -s" is adequate. That effectively gets you a root terminal for the duration of your tasks and you can effectively launch apps as root to your heart's content. And if the user won't give you his password tell him to fix it himself and go have a beer.
Speaking personally as an old school debian user, using sudo instead of su'ing to root has taken me a bit of getting used to and the option to use su instead is a welcome feature of mint. I think giving the option to have a root user for old farts like me is great. I'd like it to go further and give me an install option to get rid of sudo altogether and have all admin functions done by the root user but I think that would be asking way way too much and would cause far too much confusion for everybody. How mint does it is a good compromise imo.