We aren’t obligated to have a seudah on Chanukah. Shulchan Aruch (670:2) states, “Some say that there is a little bit of a mitzvah to have large meals…” But it certainly isn’t an obligation. Why is Chanukah different than all other holidays?
The Chidushei HaRim zt’l answered with a mashal: A simple farmer married the king’s daughter. Does anyone need to tell him to celebrate with a seudah? He will certainly do so on his own. His heart is full of joy, and he will host big feasts and invite all his friends. On Chanukah the Shechinah comes down to us, lower than ten tefachim [which It does not do the rest of the year]. We don’t need to be told to have a seudah. We are so happy, we will do so on our own! ~ R’ Elimelech Biderman Shlita