Hiring an lxml developer can significantly enhance your data handling capabilities. They can parse, modify, and generate XML and HTML documents in your applications efficiently, making data extraction and web scraping tasks simpler. They can also ensure your documents are well-formed and valid, improving data quality and integrity. Their expertise in XPath, XSLT, and schema validation further improves data manipulation and transformation. Additionally, they can optimize your system's performance as lxml is more efficient and faster compared to similar libraries. Their skills can be invaluable for projects involving heavy XML/HTML processing.