Om Malik has an excellent post on why Kickstarter works (the comments are also worth reading).  He quotes Craig Mod because this really does say it all:

With Kickstarter, people are preordering your idea. Sure, they’re buying something tangible — a CD, a movie, a book, etc — but more than that, they’re pledging money because they believe in you, the creator. If you take the time to extrapolate beyond the obvious low-hanging goals, you can use this money to push the idea — the project — somewhere farther reaching than initially envisaged. And all without giving up any ownership of the idea. This — micro-seed capital without relinquishment of ownership — is where the latent potential of Kickstarter funding lies.

Billionaire Felix Dennis wrote, “ownership isn’t the important thing, it’s the only thing.”  Kickstarter allows creative talents to get seed capital without giving up equity.