That may be question of national security i.e. ability to defend against adversary. Let's imagine 30 years from now. World is not yet united and peaceful place. Nation focusing on social nenefits, leisure time, innovation and freedom could be as economically and technically advanced as other nation focusing solely on full employment.

But they will be substantially different when facing difficult realities of war: those benefits as well may be cut and those people should go to factories, computers, fields, whatever occupation current war needs.

How do you explain a whole generation of people that their allowance will not be paid? How do you tell them that their occupation will be unpleasant? How do you train millions of people discipline, relevant skills, command-and-control?

No major nation wants to lose next war, so we are locked in full employment race.

(sorry for bad english)