The key word you used is "alpha". As the OP of this thread said, you're not buying a product, you're donating to someone (probably not a very large company with lots of resources) to develop and make something you're interested in, and in return you may get the 1.0 (or perhaps earlier) version of what you're donating for.
I don't believe it's Kickstarter's fault in any way if people view it otherwise.
It's not donations. Donations are given without return to a cause you consider worthy. An exchange is promised, but the promise is not a sale, it's "We try and make this, and if we pull it of, you get one." It's more of a high-risk investment where you already consider the money lost, the moment you spend it.
And I'm on your side: It's not kickstarters fault, if people think otherwise - still they could make that point a little stronger.
I don't believe it's Kickstarter's fault in any way if people view it otherwise.