It's not just about trading your games in.
I see this all the time in threads like this, and starts to wonder, am i really the only one, who borrows game discs to and from my friend?
Am i the only one who will bring a game to a friends house to play a game i've bought, while we're at his place, without having to bring my console as well?
Locking it to one console would suck if your console broke as well, imagine having to re-buy your entire collection if your 360 RROD'ed
You're allowed to read a book owned by someone else if you borrow it, you're allowed to bring a movie to a friend, and watch it at his place, you can borrow your friends car, his frying pan etc. why should games be any different?
whats next? locking the controller to your fingerprints to prevent friend coming over and playing your games at yoru plafce on your console, cause they didn't pay for it?