For fun: Why I Love Basic Auth:
So yes, it's easy to use and simple but so is a tri-cycle and I'd hate to have to make any miles on a tri-cycle.
Obviously, this won't work if you are hocking sluggish blogspam with less content than the titanic had lifeboats and enough javascript to track my cross atlantic voyage. Just make shit that doesn't suck and users will sign up if it is necessary. If there is no need to have users sign up don't have it.
Super Simple Value. Build on Super Simple Auth ^TM.