Here's a promising blog by Lenore Skenazy, author of “Why I Let My 9-Year-Old Take The Subway Alone,” a controversial New York Sun article.
She raises an interesting point. I grew up doing all manner of nasty things, eating snow, playing in the dirt and the woods, etc. I think that's part of why I'm so healthy. And I did "dangerous" things sometimes too-- played in the street and the woods, went for walked by myself... At the same time, there are things that I think get progressively more dangerous each year. For example, my mom rode in a car without a seatbelt and was fine as a kid. However, at the time there were fewer cars on the road, fewer instances of drunk driving, and thus, fewer accidents.
The same is true of certain health concerns. I probably wouldn't want my kids to share toothbrushes or anything. That's not because I think there is anything inherently dangerous about sharing toothbrushes, and I did it sometimes as a kid. However, thanks to antibacterials, the germs today are a lot nastier than they were back then.
Cars are faster and drivers are stupider; I wouldn't want my kid crossing busy streets without me at least watching until I was VERY confident in their judgment. The same thing is true for letting them ride a subway or bike to school. I would want to be very confident that they knew what to do if something went wrong. As for snow and playing in the woods, eh, if the snow is new and I know where the kid is it's probably gonna be fine. It's a question of the world changing. More people close together means more danger. Nastier germs means more danger.
Would I bubble-wrap my kids? Hell no. Especially not as pertains to germs. If my kid eats food that fell on the floor, good for them for not wasting it. If they drink from the toilet, well, I might want to intervene. Washing hands after pooping, clearly a good idea. Drinking from the garden hose? My mom's rule was, don't put your mouth on the actual spout and you're fine.
It's about risk analysis. Fecal-oral transmission is a good way to get a whole mess of nasty illnesses, but the illnesses you get from the kitchen floor, not so much. Antibacterial sprays and soaps are good for daycares (lots of germy kids in one place) and bathrooms; elsewhere they are literally overkill. Helmets are a good idea for biking on hard pavement; they're not so needed for sledding on soft snow. I'm not too worried about abductions, but if my kid is out alone I'm gonna want to give them a cell phone in case they get lost or are out after dark. And yeah, there are a lot of things that were perfectly safe in 1950 that I wouldn't let a kid do today, simply because the world is not as safe. There are more people, thus, more dangers. Playing street hockey on a quiet cul-de-sac is not one of them.