Hiring a Client-Side Routing developer is crucial for creating efficient, user-friendly web applications. They help in building single-page applications that load only the required resources, reducing load times and server requests, and enhancing the user experience. They have expertise in handling navigation between views, maintaining states, and managing URL parameters. Their proficiency in technologies like JavaScript and frameworks such as React or Angular ensures seamless navigation and dynamic content updates without refreshing the page, creating an app-like feel. This can significantly improve your web app's performance and user satisfaction.