shadcn/ui has quietly become the default foundation behind many AI-generated user interfaces, powering the patterns and components produced by tools like Figma Make, Cursor, and Claude. Its popularity comes from offering clean, accessible, copy-and-paste React components that developers fully own and customize, making it an ideal fit for AI coding workflows. The broader shift highlights how modern design systems are increasingly shaped by developer ecosystems, AI tooling, and code-first infrastructure rather than traditional design platforms, with many designers only later realizing how deeply these defaults had already spread across the industry.