Written from a Generation Y perspective: How many times did we hear from our grandparents, "I walked five miles to school up hill both ways." The story usually is not heard from our parents, however. The increase in scale of living allowed our parents to be driven to locations or at very least bike. Catholicgauze's generation was blessed with the same benefits but the increase in perceived crime combined with Satanic Panic, kidnapping fears, and other hysterias to limit our roaming. Today's youths are limited even more in their freedom.
The Daily Mail has an excellent article describing the end of roaming children phenomenon. The article brings up why we should care about the lack of roaming. First off is the simple matter of physical health and exercise. Geography also comes into play, though. A roving child comes into contact with a variety of natural and human landscapes. This allows for an acquired apprication of the world (or at very least different enviornments). Even in a city, different neighborhoods can educate one immensely about people and the world. Geography, even local geography, matters.