Hiring a Flex Builder developer is beneficial as they can create rich, interactive applications that enhance user experience. They specialize in Adobe Flex, a powerful, open-source framework used for building and maintaining expressive web applications that consistently perform across various operating systems and devices. With their in-depth knowledge, they can effectively utilize its unique features, such as data binding, components, and modules, to create scalable, robust applications. Their expertise in Flex Builder allows for rapid application development, resulting in quicker delivery times and cost efficiency. Their skills are valuable for businesses seeking to improve their web presence.