Hiring a HTML/CSS Prototyping developer is crucial for your business as they play a key role in creating a tangible model of your web application or site. This allows for early user feedback and testing, reducing the risk of usability issues after launch. Their expertise in HTML/CSS ensures that the prototype closely mirrors the final product, providing a realistic representation of user interface and interaction. This process saves time and resources in the long run by identifying and addressing potential problems early in the development cycle, enhancing overall user experience and satisfaction.