Aul explains having two separate implementations means more code complexity and disk/memory usage and says the goal is to make the Settings app the unified place to change all major Windows settings. When the switch will occur is yet to be determined, there are still some settings in the Control Panel that need to be migrated to the new Settings environment.
@billybobjoe2211 @brandonleblanc Having two separate implementations means more code complexity and disk/mem usage. Getting to one is leaner
— Gabriel Aul (@GabeAul) October 4, 2015
Source: Neowin