Reasons to publish source code (2)

When it can be used as publicity, mainly between free software users and developers. Usually done by companies that sell services and hardware, but sometimes also by software vendors
To reduce maintenance costs and improve it's quality and functionality, publishing it allows a much larger and more diverse set of qualified people examine the source code, thus resulting in the discovery of more bugs and providing more and better suggestions for improvements and extensions

When it can be used as publicity, mainly between free software users and developers. Usually done by companies that sell services and hardware, but sometimes also by software vendors