Developers are also users, and a part of the application they use is the source code. Having good quality source code benefits all users, not just developers.

Developers are also users, and a part of the application they use is the source code. Having good quality source code benefits all users, not just developers. Linux is where it is today because of the quality of the code. Things like "use and usefulness, usability or function" have different meanings to a developer looking at the source code.