Just the other week I came across an interesting thread on the "kanbandev" mailing-list. It was all about "have you asked the Spice Girls question?" which seems somewhat odd, if you consider that this mailing-list is about managing Software development projects...
turns out it is only about the second verse of "wannabe" : "So, tell me what you want, what you really, really want" [you can (and should) ignore the rest of the song for the purpose of this post].
That one sentence actually captures remarkably well what differentiates a shallow requirements or root cause analysis from a thorough one: Asking beyond the obvious to find out the need that fuels the obvious.
according to Jabe Bloom Steven Bungay formulated the question a bit more formally:
[...] This should be encapsulated succinctly in the form... We should do What in order that Why.
For example... We should implement Continuous Delivery in order to minimize Lead time.
But "Tell me [...] what you really, really want" seems to stick a lot better than just "why".
So thanks, Jabe Bloom, for raining this!