Hiring an AWS Cognito developer is crucial for seamless user identity management in your web or mobile app. They can implement secure and scalable sign-up, sign-in, and access control functionalities. Their expertise helps in integrating third-party identity providers, enabling multi-factor authentication, and managing user data for personalized user experiences. They provide solutions for identity-related challenges, ensuring users have secure access to your application's resources. Hence, an AWS Cognito developer plays a vital role in enhancing your application's security, user management, and overall usability.