The Holiday of Thanks

The Gemorah (Shabbos 21a) says that the holiday of Chanukah was instituted as days of הלל והודאה.  Rashi explains that means to recite hallel and say al hanissim in shemoneh esrei.  It seems from Rashi that הלל והודאה are the theme of the day and the kindling of the menorah is just a mitzvah of the day but it doesn't define the holiday.  The Riaz interpets הודאה as a reference to the kindling of the menorah.  That means he hold the kindling of the menorah isn't just a mitzvah performed on Chanukah, it is part of the definition of the day.  The Achronim use this Riaz to explain the opinion of the Rambam that mentions that on Chanukah we recite hallel light the menorah but he doesn't mention hodah.  Why the omission?  The Rambam held its included in the lighting of the menorah.    The Rambam holds woman aren't obligated in hallel, yet are obligated in neros chanukah.  What's the difference? The obligation of hallel stems from the holiness of the day and that woman are exempt from like any holiday.  However, the commandment which is unique to Chanukah, to say thanks, that woman are obligated in as well.  That could be why the Rambam says that the lighting of neros chanukah is חביבה עד מאד, for it is an act of saying thank you, which should be performed in the best possible fashion.  Rav Shlomo Zalman goes so far as to say that one who doesn't have in mind הודאה at the time of the lighting might not fulfill the mitzvah.  This idea would explain the emphasis for hiddur in ner chanukah because when one expresses gratitude they go above the regular call of duty.  The question is why is Chanukah the holiday of thanks, what makes its nes greater than every other one of Jewish history?  Rav Chayim Shmulevetz explains that generally nissim are done for a purpose, in order to save Klal Yisroel.  However, the miracle of the menorah lasting for eight days wasn't necessary for the survival of Klal Yisroel, it was merely a display of tremendous love that Hashem has for Klal Yisroel.  A nes such as this demands we reciprocate the same love and affection back to Hashem.