I think someone asked this question earlier on some other forum. Nonetheless I will answer it here.
The Customer database is the crown jewels , the Business INtelligence for a company. Its importance cannot be stressed more. If one has a list of all the customers, their buying patterns, renewal records, preferences, etc,. A company can provide specific solutions to the customer proactively. Indicators such as the revenue generated from a customers, the additional needs of the customer, customer satisfaction can help a company better understand its clients and help increase its foothold in a given sector. Marketers can target specific solutions to specific customers or industries. Statistical analysis of the customer base can lead to surprising data that can help drive growth.

 Customer databases are essential for marketers to maximize customer retention.  It is much cheaper to keep a customer than it is to find a new one.  It is essential for businesses and franchises to develop these databases and analyze them statistically to help them target new customers as well.