Hiring a JPA developer is beneficial as they have expertise in Java Persistence API, a standard for object-relational mapping in Java. They can efficiently handle vast databases, ensuring data integrity and consistency. Their ability to streamline complex coding processes can increase productivity, reduce errors, and improve the quality of software applications. They also possess a deep understanding of Java, enhancing application's performance, scalability, and security. Their skills in JPA can make the data accessing layer more robust and maintainable, saving time and resources.