If we understand the reasons, the story behind the requirements, we can implement them much more effectively. Then we know which pieces are important and which we shouldn’t spend weeks obsessively getting letter perfect. We can make a guess at what will change, and we know where performance is critical.
In relationships, if we know the reason behind a request then we can often fulfill the underlying need more effectively. “Stop picking my zits” is more effective with background: “when I was thirteen my mother obsessively attacked everything on my face and when it hurt like fuck she still wouldn’t stop.”