If it works, it works and I don't see a problem with it.
It's not an unethical approach to business just because it's an nontraditional one. As it's been said by a lot of people in this thread already, there's usually plenty of transparency behind Kickstarters and the people who back them are familiar with the risks (i.e., the lack of guaranteed delivery of a product) associated with the platform. If the crowdfunding model did not offer any value whatsoever to both consumers and developers alike, it would stagnate and eventually die off. Some people are saying SP has an over reliance on crowdfunding and I can't directly refute that one way or another, but they aren't doing anything wrong from a consumer's standpoint by utilizing it. It's probably not a sustainable long-term business model, but it's working right now.
I get not embracing kickstarter as a consumer. The value might just not be there for some people and the risk just not worth it. It also feels pretty cheeky to see a company continually not shoulder any monetary risks in developing a product. If you feel that way, obviously don't use it.