Many people find that the idea of "strength in softness" challenges everything they've ever been taught about how to be. When I say "experiment with cultivating weakness and not controlling outcomes," I really mean it. Embodying this may change your experience of the world and all the little things you do, like opening doors, picking up spoons, and brushing your teeth. I am not asking you to take what I am saying on faith, do your own experiments, trust your own experience.
That being said, it is not easy to communicate the "reason" we do certain practices, like standing still. I'm glad I didn't ask a lot of questions about the purpose of standing still when I first learned it. The truth is I made a bunch of assumptions, some of which were actually wrong. Fortunately in my case, I got help and figured it out. Most people hang on to their false assumptions (or their teachers misleading explanations) and end up disenchanted. (And here I mean both definitions of disenchanted.)
I'm not convinced that someone can understand the reasons for standing still until they have done it without fail for at least a year. Understanding would at that point emerge spontaneously in conversation. Perhaps I can sit here and type out a brilliant explanation of standing, but the truth is, it's too simple for that. The purpose of standing is that it reveals what we actually are.