Hiring a Mocha/Chai developer is beneficial as they can effectively write and manage tests for your Javascript applications. These developers ensure the robustness, reliability, and correctness of your codebase, resulting in fewer bugs and improved software quality. Their expertise in Mocha/Chai, popular testing frameworks, enables them to provide comprehensive testing, including unit, functional, and integration tests. This leads to efficient development cycles, faster debugging, and ultimately, a better end-product. Their skills can significantly enhance your development process, making it more streamlined and error-free.