I've seen too many "business requirements" which are actually implementation suggestions or complaints phrased as a requirement; and as we've all heard and read, poor requirements are the leading cause of program failure. [2]
It seems to me that the 5 Whys could be adapted to Requirements analysis as well:
The user wants a feature for X
Why? Because they use that to do this other thing
Why? Etc etc.
Obviously at some points you will have to ask Who, What and How as well.
Further proposal: All acceptable requirements will eventually find the answer: Because this feature will add value in the following area via this specific mechanism.
1. https://en.wikipedia.org/wiki/5_Whys
2. http://www.techrepublic.com/blog/tech-decision-maker/study-68-percent-of-it-projects-fail/