Switching from a "normal" (casual) writing or speaking style to a domain-specific style is known as "code-switching" by researchers, scholars, and educators. We practice code-switching when we change our language patterns as we shift from talking to lovers, to friends, to parents, to coworkers, to bosses, to clients…. Each audience expects a different style. Sometimes, we mistakenly over-compensate when we switch to a formal style, and this results in using either an unexpected code or awkwardly mimicking a code we haven't mastered.
We advise students to write more formally than they speak. We repeat this every year of their educational experiences. Many of the best students take this admonishment to be "more formal" to the extreme and over-compensate. The results include verbosity, misused "impressive" words, and strained prose. Yet, this prose receives good grades and praise, and students internalize the idea that inflated language corresponds to being "smart." Standardized tests reinforce odd writing, too.
Sadly, many academics — having been good students — cling to this stilted, artificial code. Reading some academic journals brings both tears and laughter. Not all academics are oblivious to this problem, but even those of us aware that the language has inflated to absurdity acquiesce to the trend because we also want to be taken seriously by our peers. We dare not be heretics.
When an impressive vocabulary represents the authentic you, as it did for William F. Buckley, Jr., William Safire, or H. L. Mencken, the written form seems natural to readers. (We might debate if Buckley seemed authentic or pretentious, but how he wrote paralleled how he spoke, even to friends.) Thankfully, most of us do not speak in a manner requiring our friends and colleagues consult dictionaries.
Academic writing is not business writing. Business writing is not casual writing.
Mastering code-switching requires effort. Though I argue that academics should move closer to business and technical writing, that seems unlikely in the immediate future. Students should learn academic patterns, for the sakes of their grades, and business patterns, for their careers. Yes, one uniform United States "formal English" would be nice.
Even within academic disciplines and business fields, there are distinct codes. Complicating this further, codes vary by context. And we wonder why writing confounds students?
Business writing is legal writing. When a company or organization becomes involved in any regulatory or legal action, documents become part of discovery. That legal standing leads business writing experts to encourage a style that reduces legal risk. If a reader might misunderstand a document, that creates a legal risk. Bryan Garner is a lawyer and a writing scholar. He teaches students to think like lawyers when writing. How would a judge, jury, regulator, or committee misunderstand what is written?
Academics address writings to other academics. Business writers address many audiences, including the potential audience of lawyers. That reality dictates a different linguistic code. Added to this is the reality that business writing addresses external audiences (clients) without expertise. Clarity becomes imperative.