Instead of, you know, allowing backward compatibility? That's retarded.
So...instead of enabling the people who have a 360 & games. Let's pack in a 360 into xbox one and drive up the price of every single console. ggwp
It would cut down on entertainment center real estate (and presumably make booting up a 360 game significantly faster, I can't imagine you can skip the wonderful 360 startup time without some form of backward compatibility on the new console).
Furthermore, I can't find any place that says if the console will have more than one (heh) HDMI-in, so you'd be losing a lot of the TV functionality they touted as the way of the future. I don't know for sure though. I don't know how the system works (and frankly, I'm not too interested in finding out).