«Perhaps we can offer another approach?»
How about a simple hypothesis - with very few kinks to work out?
Hanukkah I -
• Military Victory
• Political Independence
• Re-Dedication of Bet Hamikdash and Mizbei'ach -
Which in turn reflects Hag Sukkot, a celebration of the First Mikdash of Sh'lomoh haMelech
• Al Hanissim Account
• Josephus Account
• Macccabees Account
• Early Braittot including opinions of Beth Shammai and Beth Hillel - which are probably pre-Hurban
Then comes the Hurban
• Loss of Independence
• Loss of Mikdash
• No M'gillat Taanit
• No Halachic Hanukkah anymore
• No Need for Mishnayaot re: Hiilchot Hanukkah, only passive mention of what might have become a Minhag
• Spiritual Revival
• Miracle of Oil
• Sans Military or Political considerations
• Talmud Bavli [and Scholion of M'gilat Ta'anit]
• Hashgachah during Galut - reminiscent of Purim
• Hallel Now for Miracle of Oil instead of for Mikdash
1. Al Hanissim and Bavli have differing accounts because they describe different aspects based upon different eras.
2. The Mishnah was redacted when Rebbi felt that Hanukkah was "out-of-commission" Now, it is indeed possible of course that others differed during that same era...
3. IIRC none of the post-Hurban Tannaim who dominate the Mishnah are named in the Braittot, note the Mishnah re: Getz hayotzei as an exception
4. The Amoraim have a robust set of Meimrot. Suggesting Hanukkah II was in full swing shortly after Rebbi.
Just like an old battleship consigned to "mothballs" only to come back to life in a future conflict, so too Hanukkah came back to life and was refitted with a theme more fitting for Galut rather than for Military/Political Triumph.
We now observe Hanukkah II, with sparse vestiges of Hanukkah I surviving, such as Al Hanissim.