IN ADDITION to being really useful tool ... a product has to both RATIONALIZE industries in order to ensure reliable, lower cost production [to drive down costs and uncertainties of getting the viable product to market ... AND ... either eliminate or greatly simplify or greatly improve the percieved value for masses of customers when compared to the best other options
... AND ... it must also represent the best value proposition for both employees [who will likely receive stock or stock options] and early investors in terms of valuation of the company producing the product, ie it must give investors a viable exit strategy that offers the highest possible return for a given level of risk.