> There must be a reason behind the UFO media blitz
They already told us exactly why. Because there are unexplained phenomena which may pose a risk to national security, and they want to know more. Their intent is to reduce the stigma so that pilots and others are less afraid to report unusual sightings for proper investigation.
You don't have to believe in aliens to see the sense in this.
There are big holes in the theories we come up with. The inability to reconcile QM and relativity is the most famous one. M-theory requires 11-dimensional spacetime, but no one has ever observed most of those dimensions. Recent astronomical measurements, if confirmed, may falsify parts of the standard model. The list is pretty long.