I think a lot of it might have to do with space. As Scott123 has discussed before, space is a premium in most NYC pizzerias. Bulk fermentation (same day or overnight) requires less space than using refrigeration to make a like number of dough balls. Of course, that doesn't answer the question of when someone decided to extend the fermentation period using refrigeration. I suppose, there can be several answers to that question: space got cheaper, coolers became smaller and more efficient, volume management and inventory management became easier and better, competitors started doing it and others followed, profits got better, etc.