Hiring a GSON developer is beneficial as they can efficiently convert Java Objects into JSON and back. They help in data serialization and deserialization, ensuring seamless data exchange between web servers and applications. Their expertise speeds up the development process, making applications more secure and efficient. They understand how to handle complex data types, which improves the overall quality of the application. They also contribute to easier data debugging and testing. Overall, a GSON developer's skills enhance the application's performance and usability.