Hiring a jQuery UI developer is beneficial for creating interactive, user-friendly websites. They have expertise in jQuery UI, a powerful JavaScript library that simplifies HTML scripting and enhances user interface with customizable themes and widgets. Their skills can help in creating dynamic, responsive designs, reducing load time and improving site performance. They can also ensure cross-browser compatibility, making your website accessible from any device or browser. Therefore, a jQuery UI developer can significantly improve your website's usability, functionality, and overall user experience.