"Every contact we have with our customers impacts whether they come back or not. We have to be great every time or we will lose them." - Kevin Stirtz 

Retain customers and increase the chances of upselling opportunities. Why do I need to take good care of my customers and be on the same level linguistically as well as textually? 
Clearly, poor communication leads to superficial relationships, dissatisfied customers, and most importantly, fewer customers.