I vowed after my first startup never again to build an enterprise product for this reason. Plus I don't like golfing and drinking with some random guy in Omaha trying to convince him my product solves one of this top three problems.
Edit: I would also add that you tend to learn a lot more about your product from your customers. In addition, once you target a certain industry and speak to all the major players, you get some insight that helps with product, sales, marketing.