I thought the Princesses were supposed to be shown sleeping because Maleficent captured them, not because of circumstances surrounding previous plotlines (and the exception of the unlockable the Snow White scene). The apple was shown, just like all the dwarves, the hag, the animals, and other iconic imagery, because the stained glass captures the essence of those movies.
While I agree with the aesthetic choice part, I think you're underestimating the Kingdom Hearts ability to insert colors (where they aren't traditional or necessary), punch up saturation, and go gradient crazy. Strawberry blonde ain't no thang.
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