David Skok has posted an extended article about reducing churn by keeping customers happy. He sets the stage nicely: "Because most startups are created by passionate product people, they tend to fall in love with their product and its features. Often this means that they lose touch with the simple messaging around business benefits."
It does take extra effort to reach out and really understand your client's needs, business model, and best ways to make use of your product or service. It may not always pay to make the effort, but if much of your profit comes from repeat business and upsell, it may be a lot more effective to Keep them Happy than to Go Get New Customers.
Skok goes into a fair amount of detail about the need for quantifying your customer's success and happiness. Then he give a number of examples of different ways to organize your team effort to keep that customer happiness quotient up.