The problem with Oculus kickstarter project was that you were buying a dev kit, not a final product. So now they sell the company and you have a dev kit for a facebook product... and the final usage of the Oculus may be very different than the one you thought it was going to be when you purchased the dev kit.
That cannot happen with other kickstarter projects that sell a final product like bumper stickers, buttons... In this case, the only difference with a normal purchase is that you buy the product before they manufacture it, so the startup avoids taking risks.
What's the different? If the final usage of Oculus Rift is different once they sold the company to facebook, you are still going to get different final product if you buy/pre-order it via kickstarter.
That cannot happen with other kickstarter projects that sell a final product like bumper stickers, buttons... In this case, the only difference with a normal purchase is that you buy the product before they manufacture it, so the startup avoids taking risks.