Being Shown our Weakness is a Good Thing WHY?

27 And if men come unto me I will show unto them their weakness. I give unto men weakness that they may be humble; and my grace is sufficient for all men that humble themselves before me; for if they humble themselves before me, and have faith in me, then will I make weak things become strong unto them. (Ether 12:27)
I've always known I had a lot of weaknesses. You can't grow up as the youngest of five children, AND having A.D.D. and not be aware of many, many weaknesses. 
And I've felt at times that I was able to wrap my head around what a good thing it is for the Lord to show us our weaknesses, so then we know what to work on, right? But way deep down, my feeling was, "being shown my weakness is a good thing WHY?"
But a week ago, in the YSA ward, we were talking about this in S.S. class, and from somewhere came into my mind the visual of the Savior washing the disciples feet. Peter objects, knowing that Jesus was the Messiah, the promised Savior. But Jesus says, "If I wash thee not, thou hast no part with me" (John 12:8). 
It hit me. If the Lord does NOT show us our weakness, and if we do not LET Him show them to us, we have no part in Him, nor He in us. He cannot help us, lift us, save us, if He is not allowed to "wash our feet", or "see our (life) nakedness." If we don't offer to him, in full disclosure, all our warts, failures, guilt, and so on.