Why proper grammar is important in the business world?

Proper grammar is important in any form of communication, simply because it helps to ensure that your message is transmitted in the clearest manner possible. In business, this is especially important

• not only do business communications affect the idea customers,

clients and other businesses have of a company; many business communications have legal ramifications.

The unfortunate result of businesses twisting Words (particularly adjectives) to take on a new, more marketable meaning is that many business communications are meaningless at best. I would add to this answer that the manner in which you write can also provide a perspective as to who you are and what your intentions might me... experienced business people take notice of subtle differences and make quick inferences.