Things aren't different, shefner. In fact, since the 1950's, stranger abductions have remained constant, even recently dipping a little. What has changed is that we know about it immediately when it happens through this wonderful/horrible internet. We have come to believe that 11 year olds aren't safe in public. Eleven year old girls scootering together along main street are exceptionally safe - they are MUCH more likely to have a scooter crash that causes their death than come to harm by a stranger. I think we are in danger of raising a generation of children who simply cannot function as adults because they were never allowed to learn those skills of making decisions, taking risks, working things out when they had a problem. An adult has always been RIGHT THERE to do it for them.
Don't feel badly about allowing your girls to live normally. That's your job as a parent.