The evolution of Drupal's contributed code governance, as detailed by contributor Angie Byron, highlights a journey from an open-door policy to a more regulated approach. Initially, anyone could contribute, leading to chaotic contributions. Over time, stricter processes were introduced to improve code quality and security, culminating in a shift towards an opt-in process for security team coverage, significantly impacting contributors and end-users. This change aims to balance open collaboration with security and quality control.