This is a good question. The role of market research is essential in any business. The reason for this is threefold. First, in order for a business to succeed, what you need to do is know your target group. You need to know their spending habits, what they want, what they need, and the like. Second, based on this information, what you need to do is to create a product or service that this group would desire or want. Market research can help in these areas and should be conducted right from the beginning.
With that said, market research can also be of continued help in a third way. Market research can also better a product or service. If you know how to improve your product or service, then you can even be more successful. There will be repeat customers.