This one in particular, the Grimm version.
Ok, I'm gonna try and guess why it flew over everyone's heads.
Firstly, the actual name of the princess in Sleeping Beauty is something I don't think a lot of people (at least in english-speaking countries) care about. The brothers Grimm version calls the story "Little Briar Rose" and the princess is named Rosamond. But to english-speaking countries it's "Sleeping Beauty", with Disney's version being extremely poplular, the name that version has is Aurora. (I know the grim bros. are german and the folktales they compiled are originally germanic and stuff)
Secondly, the plant-theming with the Thorns was so overt, that I think readers just went "oh hey, these dudes got a plant theme going on" and didn't bother to further analize.
Thirdly, its just counter-intuitive? Instead of breaching the thorns to save a princess, Ciel and others fought goons to try and stop the syndicate leader, Rosamond (the "princess"). Plus, she was also concious and active the entire time...kinda the opposite of the story to begin with.
I know the brother's grimm version of folktales got back into the public eye in the last decade or so
TL;DR: Disney too popular, overshadowed other versions and and thus people who speak english as a first language didn't catch on to all the references.
...So how much Hinduism stuff did we miss with Parvati or was there nothing?