As I've written in my unknown blog, I think there is another misunderstanding here: software development is not the analogy to building something according to a plan. It is making the plan. http://blinker.net/2009/08/31/the-architecture-analogy-for-p...
Jack Reeves is the man here though - writing source code is designing the product. Before code can be written you need to take all the trade offs, the decisions and the research (or just make wild assumptions).
Once you have source code, it has been designed.
Which is why instead of sending out a 12 page form telling a client they need to think harder about something they don't understand, put out version 0.1, and ask them what they want changed.
