While I respect each and every one of the very personal and difficult decisions that you have all made about your children's safety and wouldn't dream of suggesting that anybody does anything that they are not comfortable with themselves............I do feel that such decisions should be made possibly from a more informed viewpoint than some of the knee-jerk reaction to media hype that some of your views sound like.
I have two young children myself and find it a constant battle with my concience to try and ignore the over exagerated media reports that would scare us all into keeping our children inside under our wings until they were 21. At the same time I accept that each sad case is in fact some parent's child.
That aside there are actual researched facts that would help a parent to decide at what age it might be safe to let a child play outside.
I can't find the actual research reference but this leaflet from a police force in Canada refers to it
http://www.mjpolice.ca/pdfs/Child%20Pedestrian %20Safety.pdf
This suggests that before the age of 9 children are at a much greater risk from traffic than they might be at an older age, traffic being a much more real risk than the perceived risk from stranger danger or "the bogeyman".
This would suggest that unless you live in a very quiet traffic free street then to allow a child to play in a street unsupervised might not be the best practice.