Faraday, after demonstrating how moving a magnet through a coiled wire induced a current in the wire was asked by a visiting statesman what was the use of this.
Faraday responded, "In twenty years, you will be taxing it"
Similarly, at a demonstration of hot air balloons in France, Benjamin Franklin was asked "Of what use is this?"
Franklin replied, "Of what use is a newborn baby?"
Read about this yesterday, and from comments on the original Twitter post, it sounds more like CBP decided child porn was involved. Either they intentionally destroyed the floppy because they assumed that's what it contained, or they thought the floppy was actually just hiding something else (such as a mini CD or DVD?)