Hiring an developer is beneficial for creating dynamic, user-friendly web applications. They can enhance your website's interactivity and responsiveness, reducing the need for page refreshes. They're skilled in JavaServer Faces technology and AJAX, making them capable of integrating AJAX functionality into JSF components. With their expertise, your web application can provide a seamless user experience, improving customer satisfaction and engagement. They can also ensure compatibility across different browsers and devices, increasing your application's reach and usability. Therefore, an developer can significantly improve your web application's performance and user experience.