They *are* including other holidays, just not enough to OP's liking.
1. They include Hanukkah in the Believe in Holiday Magic fireworks show
2. They have a band playing Hanukkah music
3. They play Hanukkah music over the PA in DCA, and on Mater's
4. They sell Hanukkah merchandise
5. They offer a twist on Hanukkah food at the Festival of Holidays booths
5. They offer baked items in Hanukkah colors
6. They have Hanukkah crafts
7. They have a description of the history of Hanukkah (and other holidays) in DTD.
8. They have Hanukkah themed store windows.
9. They even offer
Hanukkah Disney Parks wallpaper for your phone.
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