> why would we want to lose all of that information.

Because the url past the domain name is not for the user to be messing with most of the time. We the developers control everything to right of the first single slash. Maybe if it was hidden then it would force us to do a better job showing the users where they are in our sites with breadcrumbs and menus and at the same time keep them from trying to poke around in places where they shouldn't be. I think this is a perfect opportunity to open up our minds and build better UI inside the frame.