The Ikker Pirsumei Nisa is about the Ness of the oil. We thank Hashem for the Yeshua as well, but Chanuka was not established because of it. There were other Milchamos that we won. This one stood out because of the Ness of the Menora.
Purim, on the other hand, is all about the turn of events. On Purim we remember and focus on the Vinahapochu.
The Kriah on Pesach is not equivalent to Megilla, because it is not from the Mitzvos Hayom. Besides, reading about Ribis, although it mentions Yetzias Mitzraim, is a far cry from reading Parshas Shmos through Beshalach.
On Pesach we don’t need a Megilla or a Chiyuv Kriah because we have Pesach Matza and Marror, and there is a Mitzva to be Marbe Bessipur Yetzias Mitzraim. But mostly as I said, on Purim the whole point is Vinahapochhu, which is all about the turn of events.