Your face, license plate, IP address, etc are all also "public data" in the same sense. When you have large scale aggregation and dissemination of this data that still can create grave privacy and safety concerns.
I strongly believe that aggregation of many types of this sort of data should be made illegal by privacy laws.
I am less sure if those laws should cover flight location data, but it seems like a discussion worth having. We need to weigh the privacy and safety loss against the transparency gains.