Though Apple's expensive headset was been praised for its cutting-edge technology, the device is expensive and hasn't yet been widely embraced at either home or work.
What's doublely stupid is that a developer would have to spend the exact same amount of money to be able to develop an app for the headset. They're not going to do that unless they reasonably sure they're going to make their money back.
Probably the dev would have to spend more, usually Dev kits come with a bunch of handy features for debugging/testing, but including SDK and licensing yeah, more money.
this does raise a good question, if apple intended this as specifically being for developers, why aren't they marketing it as such and encouraging devs that they will release a cheaper headset later?