Why Use Kickstarter?
Or more to the point, "why don't you get a small business loan to launch?"
By operating in that pre-sales mode Kickstarter provides a security blanket for both the (potential) business owner and the customers. If the project owner creates a solid budget model, a successful Kickstarter campaign essentially means that there's enough customer interest to launch at least a first run of a product. If the campaign doesn't succeed, many risks are avoided -- some to the business owner, but also some to the customers. (Such as the "I bought this product but then the company folded and no one supports it" scenario.)
I.e., assume that you have to produce at least 2,000 copies of product to get a reasonable manufacturing price. If 2,500 copies sell via a Kickstarter campaign, the product is launched, the first customers are immediately fulfilled, and there should be enough profit from that production run to produce a second wave. The Kickstarter backers receive the special rewards offered during the campaign (plus the satisfaction of having been a business or arts supporter.) Risk is mitigated for both the business and customer, and everyone wins.