Those pins where pretty important. his dad and grandpa wore/forced everyone to wear them also. They where probably forced by Cia's Handlers (check out CCP Greys video "Rules for Rulers" of how 'absolute dictators' get their power, and who REALLY controls the countries. The 'figurehead' rarely has the power they pretend to, but in personality cults it is imperative that everyone THINKS they do.
The pin disappearing is very significant. It is probably the first steps of undoing north Korean brain washing.