It helps to be car dependant for some time in your life. I don't mean to have a car for joy riding, but to have a car that you drive to school/work day in and day out. Once you realize how little attention you pay, and how much of an automaton you become, you can get rid of the car.
It's good to realize how little one can actually see outside of a windshield during a down pour. Or how little control you have over a car on ice (if you cycle in winter).
It's a sobering experience to realize what is out there waiting for you on the roads.
Just my $0.02 after I read the "teen going car free" thread (or parts of it).