Ever since our county library system's big book giveaway last September, I've made it a priority to borrow the older titles on my "to-read" list before they are removed from circulation. So most of the books I've read in recent months were published in the late '80's or early '90's. I've been surprised at how much richer the vocabulary is compared to recently-published books aimed at a similar audience. I've found the need to keep a dictionary handy while reading because I keep encountering unfamiliar words.Absolutely.
Vocab in books published prior to the 80s is much larger and more varied.
And: lots of the SAT Critical Reading passages are drawn from books published prior to the 70s.
A couple of years ago, I bought a copy of Penrod for C and was astounded at the difficulty of the vocabulary. I loved the book as a child, and I doubt many children today could read it.