If have heard not one single tangible bit of evidence from anyone
that requiring a picture ID for pilot license will do anything
to justify the cost and inconvenience when it comes to enhancing
national security.

There hasn't been a single case of terroristic use of a GA airplane
that I am aware of. The whole case in question revolves around 9-11
with commercial airliners and did not even involve the pilots. It
was a failure of a governmental agency to determine whereabouts and
activities of foreign nationals (i.e. non-US citizens).

In my opinion the whole picture ID thing is feel-good lawmaking
that will cost more money and inconvenience in order to provide
an illusion of greater security. It is akin to locking the barn door
after the horse has escaped. When it finally becomes obvious that
the measure did nothing to prevent future attacks there will be
even more measures and restrictions which will be proposed.

This is my opinion and I'm sure most people will disagree with me.