The Authenticated Users role is so that it is easy to make pages in the content system that are only visible to authenticated users. Since pages already show or hide based on role membership this was more simple than adding another check for isAuthenticated. When new users are created they are automatically added to the authenticated users role.
I will consider these ideas for role implementation. If you would like to implement a new IsSystemRole column let me know. Otherwise, for the moment I will add the Role Admins to the non-deleteable role and make sure all data layers are consistent. In my view the current role sytem is decent and I would rather work on new features that will make mojoportal more popular then spend all my time polishing little things to perfection when they are already working well enough.
My time is my most precious resource and I must choose carefully how I spend it. If I fail in making mojoPortal popular then I will also fail in making a consulting business around it that can sustain me. If that happens then I will be back working in the corporate world with no time to work on mojoportal. I think at some point the popularity of mojoPortal will reach critical mass and I will no longer have to worry about the possibility of my new business failing but until we reach that point I have to be very strategic in what I spend my time on to advance the success of this project and my business. If I spin my wheels too much on little things I won't accomplish the big things.