I dont think that we can control our lives according to the 0.01% of sickos out there. Like what Hoobley says, if you are always wondering about who's watching, you dont get to live your life to the fullest, and for kids I think the freedom is paramount!!!!
So I think its fine for kids to be nudies at the beach until about 4 or so, but different at a public swimming pool where I think togs are a little bit more required. I think kids are fine to get changed in public (like beside the car or on the beach) until they are maybe 6-7??