Predators of children are usually someone they know personally, not a stranger. I think we've made great progress in recognizing that this is the case, and better preparing our children for it. I also think that we've become more willing to have a public discussion about these kinds of offences, and speaking out is now more acceptable (as opposed to hiding an incident out of fear or shame).
Yes, we have made progress in children's safety from predators in the last 50 years, because we keep a better eye on children than we used to. When our generation was young, we used to go outside and just be gone all day. If we went missing, no would notice for an entire day. We pay more attention now.
From the recent reports that I have read, crime is way down from even 20 years ago. I think parents are more aware of the fact that most predetors are someone you know and not a stranger off the street. I think the amber alert also helps find children much faster than in the past.
It used to be that kids could play outside, that they would ride their bikes and play with one another in their neighborhoods. Now, parents force their children to stay inside, and most of their lives are spent without having any fun whatsoever. The reason these kids are getting taken is due to over-exposure to family members or other negative influences. It is the family's responsibility to give freedom to their kids, not imprison them in basements.