I think you miss the point of doing "Fantasy in the Sky" on New Year's Eve: They do that because it is a real, straight-up fireworks show, which you would expect for New Year's Eve, as opposed to a story-heavy show. It's a night suited more for celebration and revelry, not so much a dramatic tale of good and evil characters set to pyrotechnics.
Incidentally, I might note that they used to return to an independence day version of "Fantasy in the Sky" for July 4, before replacing it with a new Independence Day show, which IMO was back toward story again -- although musical --and not quite the right move for July 4. The new one, while patriotic still, is a little to moody in its music, where, like on New Year's, it should be over-the-top celebratory and full of revelry. A straight-on fireworks show with amazing musical accompaniment of a patriotic nature. (We are talking Walt Disney's Main Street, USA, for goodness sake. Where else to have the quintessential -- if not stylized -- American Independence Day fireworks show?)