That it’s required doesn’t mean that it adds value.
I’ve long been of the opinion that involving as many stakeholders in the project as early as possible is a key to successful business analysis, and, more importantly, to successful projects, and have said as much in a few of my posts on this site.
Jim Highsmith, in the book Agile project management : creating innovative products, thinks that the reason projects tend to have so much documentation and so few results is that:
“Functional specifications documents lead to an illusion of agreement. A bunch of people agreeing on paragraphs of text is not real agreement. Everyone is reading the same thing, but they’re often thinking something different.”