I think the real cleverness of that book is the comparison of 2D creatures to 3D, and use that to guide our otherwise non-existent intuition of what 4D space would look like. I could imagine one thinking of that analogue before reading the book, making it seem less novel. But you have to remember that we've lived in a society that's had that book for nearly 150 years, so it would not be surprising if some of the ideas from the book became a mainstream meme.