I believe that the xbox 720 should be backwards compatible. There are people that have never had an xbox before . If the xbox is backwards compatible, then the buyer will have an instant library of games to choose from. If the xbox isn't backwards compatible, it might keep the consumer from purchasing a new console because there may be quite a few games that they never have played before.
Yes, I absolutely think that the XBOX 720 should be backwards compatible. The XBOX 360 is backwards compatible with the original XBOX, although a physical hard drive is required. Microsoft should consider that a mandatory feature that all new XBOXs should have, because otherwise, gamers with huge collections of games would have no incentive to switch to the 720, as having to own both consoles in order to play their favorite games would be a huge inconvenience. Another reason is because there are many games that come out in November of every year, and there will be at least 10 or so brand new games which would effectively be rendered useless when December comes and the new 720 comes out, including Call of Duty: Ghosts, which Activision has already confirmed will be tailored to the XBOX 360.