I was once told that "If you want to sound smart, use words more than three syllables long." Well, these three plus syllable words are usually Latin aspects of the English language as Zinsser writes before the quote above. But is precisely these big, long words that tend to make listeners' and readers' eyes glaze over. That may be precisely why officials people in charge (or who want to be in charge) use such long, somewhat ambiguous words: to confuse those who like simple Germanic-based words in the English language. Using big words immediately sends a statement to whomever is listening/reading that you're smart and you know what you're going on about, so don't interrupt you.
But I wonder, if it was not tradition or society's expectation (Latin words) that people in high places use such words, would they use short ones instead? I think they would. Unfortunately, it is the common expectation that individuals utilize significant verbal designations. People seek to mostly cleave to society's traditions, because "that's the way it's always been done," but maybe its time to start a new tradition of using short, emotive words? Problem is, who wants to face the suits?
Just remember, I'm not the only one with ideas relating to Zinsser's article, check out my coursemates' replies.