I agree with you on this, and an in-depth market research needs to be done to be sure the business actually fits or solves people's problems in real time (not in theory alone), once that is achieved ensure you know your target audience, this will help you focus on them and get you returning customer.To my descretion. I think brainstorming on existing business could be okay. But try figuring out the usual or normal way of the business model then try attaching a unique system to the existing ways of running. That could make it stand out from other vendors running it. Uniqueness and Branding is the key success to every existing business.