Why make your design system public?
Brad explains that making a design system public: Increases its visibility, which therefore increases the likelihood of use. Creates accountability by demonstrating a commitment to a product dedicated to consistency and reusability.
Why do design systems matter?
In short, you need a design system because it speeds up your work by making the product team more efficient, and it creates consistency and harmony within the product and brand ecosystem. A strong design system takes the burden off individual designers to think through commonly recurring design problems.