Correction: Chanukah does not celebrate the victory over the Greeks nor the "launch" of the Hasmonean era. As the name suggests, it commemorates the rededication of the Bais Hamikdosh. As for the Hasmonean era, note that later generations of the Hasmoneans became as corrupt and Hellenized as those the Maccabee generation revolted against. Unpopular among the people, and not recognized as legitimate kings by the rabbis (they were Kohanim and not from the Davidic line), the Hasmoneans faced a lot of turmoil from the people and eventually requested help from Rome to restore order. Why would we celebrate that?
Correction: Chanukah does not celebrate the victory over the Greeks nor the "launch" of the Hasmonean era. As the name suggests, it commemorates the rededication of the Bais Hamikdosh.
As for the Hasmonean era, note that later generations of the Hasmoneans became as corrupt and Hellenized as those the Maccabee generation revolted against. Unpopular among the people, and not recognized as legitimate kings by the rabbis (they were Kohanim and not from the Davidic line), the Hasmoneans faced a lot of turmoil from the people and eventually requested help from Rome to restore order. Why would we celebrate that?