[tonyedgecombe]

All the while I was consulting I never met a client who knew what they needed until you started putting something in front of them.

Some of them had already produced detailed requirements documents but those documents never really represented the reality.

[WorldMaker]

The industry is also full of so many stories of a developer trying to say "Thinking ahead, I don't think you want X because it won't do what you really want which is Y", getting nothing but "Just do X, that's what we researched and PMed into all these requirements documents" to only be followed by complaints of "Why doesn't this do Y? That's what we really need." when presented with "finished" software based on the requirements.