Improving code quality through proper package visibility is crucial for enhancing reliability and maintainability in Go programming. By applying visibility constraints, developers can better manage access to struct fields, ensuring that users interact with methods rather than directly modifying properties, thus reducing potential bugs and unexpected behaviors. The lesson highlights the importance of using constructor functions to initialize struct values securely, while also addressing common pitfalls associated with passing parameters incorrectly. By structuring code this way, developers can enforce better practices and create a safer interface for package users, ultimately leading to more stable code during development.