Why is clear writing so important?
Because, as my wife has often reminded me, you get only one chance to make a first impression.
Which also reminds me of the single most-often repeated line from wives to husbands: "Is that what you're wearing?"
Our writing clothes us — either in precision and clarity, or in raggedness that turns off a reader and, worse, a customer. Careless errors in spelling or grammar undermine trust. So does roundabout sentence construction, to wit:
"The reason for my resignation was that it had become clear to me that the company expected me to do two jobs for the salary of one."
That sentence can make you feel like being driven from Minneapolis to St. Paul by way of Green Bay, Wis. Instead of a brisk 11-mile jaunt between our two downtowns, you agonize through 277 miles to Green Bay and 277 miles back.
Better to write: "I resigned because the company expected me to do two jobs for the salary of one."
That eliminates the weak verb "was," and it economizes by eliminating "it had become clear to me that …"