I also grew up when we would leave the house in the morning with our skates on and walk (slide) to the outdoor rink and my mom would be dragging me home by the ear after dark. We did the same for baseball, soccer, road hockey, cops and robbers, hide and seek, you name it.
I have 2 young children (6 year old girl & 4 year old boy) and so far have been blessed with children who want to be outside all of the time, in fact we just got home from soccer. Being an IT guy, I see the kids sitting on their computers or video games all day long and I am making a conscious effort to get my kids doing activities instead of playing with technology. Now mind you my kids are still pretty young, but I think if you make the effort to get them moving young, it can pay off later.
I will say that times have changed, and that presents a challenge for parents to allow their kids the freedom to roam the streets like we did at such a young age. This just takes more effort on the parent’s part to be more involved. We just purchased a trailer for camping (well you can't really call it camping) and have it at a beautiful seasonal campground that is full of families. The kids have made a bunch of friends and take off in groups (or gangs) and are gone for hours at a time. They go go go all day long, get lots of exercise and are ready for bed early. This seems to be working for us.