Three main reasons.

1) Going through resellers and distributors adds a signficant premium. By using Kickstarter, we can sell the kit at a reduced price.

2) Kickstarter enables us to communicate directly to indie developers, makers and other hackers and get their feedback on the product.

3) The funds will help us accelerate development for the open source software stack.

Other companies have used crowdfunding to launch products recently, including Canonical, Sony and - more recently - Pepsi.