I always stressed using an 'expanded vocabulary' with my children, and making sure they were never afraid to ask what something means. They are all very comfortable using 'big words.'
My younger daughter is currently working in insurance, where part of her job is sending letters to policyholders. Her boss goes over her e-mails before they go out, and my daughter constantly gets her e-mails corrected. The boss told her the average American reads at a 6th grade level, and that she has to dumb down the e-mails, otherwise she may offend the reader by making them feel stupid. Her boss even told her she's had to go to the dictionary to check the meaning a word or two that my daughter used.
I am both very proud of my daughter, and saddened by the poor reading skills in this country.