Hiring a Kinect API developer brings multiple advantages to a project that requires motion-sensing and interaction technology. First, they bring a high level of expertise in Microsoft's Kinect technology, which can be used to create immersive, interactive applications for a variety of sectors, including gaming, healthcare, retail, and more.

Second, Kinect developers can leverage the API to create robust applications that can track and interpret human motion and gestures. This can result in highly innovative and engaging products that offer a unique user experience.

Third, these developers can also utilize Kinect's advanced voice recognition capabilities, adding another layer of interactivity to your application.

Fourth, they can help you tap into the potential of augmented reality (AR) and virtual reality (VR), both of which are rapidly growing fields.

Lastly, a Kinect API developer can ensure that your application is optimized for the Kinect hardware, ensuring smooth performance and a high-quality user experience.

In short, hiring a Kinect API developer can give your project a competitive edge by leveraging cutting-edge technology to create immersive, interactive applications.