Market segments gives you the opportunity to get to know your customer and concentrate on their needs. It also contributes to the overall quality in products as well as the business performance. Hope that helped.
A useful market segment:
1) is possible to quantify.
2) is sizable enough to profit.
3) is constant enough to not disappear after some time.
4) makes it possible to reach potential customers promotion and distribution channels in a cost-effective manner.
5) provides supporting data for a market positioning or sales approach.