this is the same vein of question a third grader has asking why he should learn how division or multiplication works when a calculator (or computer) can do it better and faster no matter what... which is akin to asking why learn carpentry when a drill can place screws more perfectly than you twisting the head with your thumb and forefinger.

It's important to have an understanding of the fundamentals of your task before relying on the tools to do the complex version of it, so you can reason about the next step and decide what the task is, not just how to do it.