Its funny how everyone is talking about the used games. That is just a shadow for the real problem, what happens to your games if you forget your account password? Say your xbox one breaks down so you don't play for a few months or a year, you buy a new xbox one then you find out your old hard drive isn't compatible with the new hard drive it happened on the slim version for the 360. Then you go to transfer your games over but you cant remember your email or maybe forgot your password. You can then kiss all your games goodbye because there all linked to that account. Go to the main xbox support page and look at how many people forget there account information all of those people would have lost there games to there hard drive and will have to repurchase everything. Sure this is how most pc games work but that was the convenience of owning a console. On top of that accounts with high gamer scores will more then likely have more games linked to there accounts, raising the value of those accounts in turn making them bigger targets for hackers.
Simple solution they made CLOUD STORAGE. Account information can be re-obtained with security questions and passwords reset anyway It don't matter what they say gamers will still buy this console as well as they will buy the PS4. It's the next gen console people will want to get their hands on the new piece of equipment It's like anything new people want the new and shiny stuff