Advantage of watching what specific customers pay, not just what they say, is that this enables the tracking of lifetime purchases, a critical ingredient in determining the lifetime value of specific customers and customer segments. To be
profitable, investments made to increase satisfaction and value must focus on the customers with the highest potential value. Satisfaction research applied broadly across the entire customer base,while statistically correct, ensures that scores will
be influenced by the responses from unprofitable customers. For example, a bank branch manager might hear many complaints about long teller lines but the most profitable customers may not care.
Source : loyaltyrules.com