Because if God only created creatures that He knew would love and obey Him, He would be tyrannical, narcissistic, and a monster.
If God created in a self-interested way, seeking only to bring Himself love, worship, and praise, it would make sense to only create that which He knew would sing His praises and to either obliterate or refrain from creating any potentially defiant entities.
Thankfully, God does NOT create out of a self-interested way or out of a necessity to make up for a deficiency or defect in His existence that can only be perfected by creating pre-programed worship machines. Instead, God creates us out of Love.
God creates of His own free will; creation is lovingly willed from Him for eternity. He creates both angels and us with free will so that we can freely choose to love Him. He does not taint this free choice with threats of annihilation, nor does He refrain from creating that which would not choose Him. Rather, He gives each created being freedom in their existence; freedom to choose Him and His will or to reject Him and instead cling to our own will.
In doing this, God shows us His love; He sacrifices some of His own freedom and control. He “shrinks into” Himself to allow for there to be a “not Him” so that we have the freedom to choose something other than Him. The problem and evil of the world comes because where there is not Him, there is also not love, not compassion, not forgiveness, not joy, and not hope.
God remains silent in the face of evil because He lovingly restrains Himself from overwhelming His creations into a forced conformity and false “love”. Consider the silence of Jesus when facing His accusers; His absolute restraint of Himself and His power to allow for the transpiration of the greatest evil ever perpetrated. Why would He do this?
Because He knew He could bring about the greatest good from the midst of the greatest evil.
Consider Adam and Eve. Why allow them to be tempted? Why allow them to fall? Because He loved them. He knew that even though they would face temptation and fall, He could bring about a greater good; He could more fully and perfectly reveal to them, and all of humanity, how great His love for us is. His love would be more fully manifested and developed with the introduction of forgiveness, sacrifice, redemption, and eternal salvation.
God is Love; if we choose not Him, we are also choosing not Love, and everything that goes with it. He allows the shadows so that we may better see the light.