4:136 انزل نزل
Quran is very different in both its content and its nature of revelation than Torah. Quran focuses on both Kitab and Hikmah parts with equal emphasis along with another objective of preserving the itmam-e-hujjah of Rasul till the day of judgement, while Torah on other hand, was mainly focused on Kitab part because their immediate job (i.e. Bani-Israel) was to establish Shahdah on other nations in the presence of prophets living among them. Therefore, its true that it seems like Deuteronomy was a final arrangement but considering the nature of both their contents and the purpose they were meant to serve, it can be easily said that Quran indeed required a more elaborative and gradual approach.