At some point, your kids might demand the ability to walk home on their own before you have a chance to make it your decision
I'd never poke fun at anyone for being concerned for their children, but I just always wonder how we made it to adulthood given all the things our parents did which are now considered stupid ...
There really is no more danger to kids these days than there was when I was little 20 years ago ... therefore, based on my experiences at that time, I'd have to conclude that when the time comes, my son will be OK getting to and from school by himself from an early age, though I appreciate it's something you're not comfortable with.