This. I have spent the last 10 years preaching this to clients and other developers alike and I spend a good amount of my time writing documentation that define

This. I have spent the last 10 years preaching this to clients and other developers alike and I spend a good amount of my time writing documentation that define software projects; and customers pay me to do so. I love doing it actually and the way I sell it to customers is this: "Changing the document is much cheaper than changing the software."