Hiring a Javadoc developer yields numerous benefits. Firstly, they contribute to creating well-documented code which is critical for the maintenance and future development of software projects. The Javadoc tool enables them to generate API documentation in HTML format from comments in the source code, providing an easy-to-navigate interface for understanding the software's structure.

Secondly, they help ensure code consistency. With their expertise, they can implement a standard way of writing comments and descriptions so that any developer, regardless of their experience level, can understand the code's functionality. This enhances collaboration and knowledge sharing within the team.

Thirdly, Javadoc developers can effectively save time and resources. Instead of spending hours trying to comprehend complex code, team members can refer to the generated documentation. This improves productivity by allowing developers to focus more on coding and less on understanding existing code.

Fourthly, Javadoc developers are instrumental in creating self-explanatory, reusable code. This is especially beneficial for open source projects where the code needs to be understood by developers globally.

Finally, they facilitate better software design. By writing Javadocs, developers are forced to think through their design decisions more carefully, leading to better, more thought-out software architecture. This can significantly improve the quality of the software project.