Hiring a Datanucleus developer is beneficial due to their expertise in managing and manipulating data across a wide range of datastores. They can provide solutions for storing, retrieving, and querying data, ensuring efficient and reliable data management. Their knowledge in various database types contributes to building flexible, scalable, and secure applications. Furthermore, their proficiency in Java Persistence API (JPA) and Java Data Objects (JDO) standards can help create a seamless data layer for your applications, boosting performance and productivity. They can also help in migrating datastores, ensuring a smooth transition with minimum downtime.