An interesting perspective. I too would like to spend more time writing open source software. The main reason I do not, and something which I think holds true for a lot of people, is that even if our company wanted to open source some of our software it's fairly difficult to do so and of questionable value.

Many of the components and practices in our software are quite specific to our business and environment. They'd just be useless or, worse, an impediment to other people wanting to reuse the software in a different context.

Even if we were to refactor parts of our code base to produce some "clean" components that didn't rely on the specifics of our business or other processes, there are many cases where that would just add to the overhead of maintaining the software for us.