Whatever your idea, it is supposed to turn into a service or a product that will people will use. It has no value otherwise. Market Research is part of your business development process. It is done before your marketing strategy and your go-to-market plan, because you first have to know what field you are even playing in.
Market research, when done properly results in accurate positioning, branding, niche selection and the way you define your venture and present it.
Market research is also a part of any due diligence because in the process, we map competitors, we look at pricing and business models and we then decide how to proceed.