Duster quarter windows

Has anyone ever wondered why when the Duster/Demon/Dart Sport were designed they didn't make the rear quater windows roll down? I know they were designed to be a cheap affordable hot rod but the Dart/Valiant/Scamp all had roll down rear quarter windows so why not the rest? This is the only thing I've never liked about these cars and have often wondered if there is a way to customize the car to make it possible to have this option even though it would probobly be far more expensive then what it is worth.

Thats my 2 cents....