“Human reason can neither predict nor deliberately shape its own future. Its advances consist in finding out where it has been wrong.”
– Friedrich August von Hayek
Man is a rationalizing animal, not a rational animal. It is the struggle to live a rational life that marks the evolved human.
In early/primitive societies with small numbers of individuals, "why" provides the simple answers that allow for survival. Even if the explanation is wrong, the speed at which the answer can be arrived at is more important than the accuracy when survival is at stake.
However, as society becomes more complex, “why" is not the question we need to ask ourselves, but rather "how". By understanding "how", we will likely come to understand the correct answer to "why”. Defaulting your questions to "why" leads to answers that all too often are simplistic and have emotional roots.
Why did this person have to die? Why did this natural event have to destroy all we have? Shaking your fist at the gods provides emotional relief; however, looking into what led to the event is more likely to provide meaningful answers that can influence your future choices (the person smoked for 20 years and died of lung cancer, the city was built in a flood plain, and the levees were not maintained).
Religion is an example of what the simplistic search for "why" leads to. Once the "answer" has been supplied via dogma, thinking shuts down, and the ability to even see alternatives is cut off. Only by using "how" as our guide can we really see the full chain of events that led to what happened.