Wrapping every purchase in a binding arbitration agreement is absurd. It completely defangs consumer protection laws.
You're not purchasing anything on Kickstarter though, you're making a donation.
When you pledge to a kickstarter, they're committing to providing the rewards stated for the money provided.
The difference between that and a standard purchase is that the product generally doesn't exist yet, which is why there is a risks section attached to every campaign, so that backers are aware that the product could run into problems.
However it's not a donation.