If you want to run a successful business, you do!
Marketing is about taking goods and services from an idea to a purchasable commodity that a customer can appraise. It includes the conception of a product or service, setting a price that is acceptable to the market, establishing how it is to be taken to market and the development of a promotional strategy.
Consider a shop without a shop window in which to display its wares, it may not do very well in any high street.