Proper use of the English language is not some exercise in academia. In today’s digital age, your words are the face of your organization. Poor language makes the organization appear stupid and unprofessional.
Kyle Wiens, in his recent post in the Harvard Business Review states that he won’t hire people without proper command of English regardless of how qualified they may be.
So, when you practice the rules of grammar for the SAT or the ACT, please do so knowing that good grammar is a skill you will need to get hired! This should be enough motivation to learn how to write properly.