Some things cannot be fully comprehended. Infinite things, eternal things, matters of God's sovereignty—these transcend our finite and temporal minds. For example, why did He create us? Certainly He doesn't need us, for He existed in perfect love and unity before He even created time. Furthermore, He even knew beforehand that His image, recreated in man, would reject Him and His Kingship over their lives, resulting in unthinkable pain and suffering and death of all things placed in man's dominion. He foresaw ruinous mutations, debilitating injuries, devastating cancer, etc., as consequences. We can only approach an answer to this unanswerable question by following the hints given in Scripture.
In a more ultimate sense, God knew that man's sin would force His only begotten Son to die an unthinkably horrid death in sacrificial payment for man's sin, and that ungrateful man would even carry out the execution, for Scripture identifies His Son as "the Lamb slain from the foundation of the world" (Revelation 13:8). In order to accomplish this fully sufficient sacrifice, the Son willingly set aside aspects of His deity, and "took upon Him the form of a servant, and was made in the likeness of men" (Philippians 2:7), forever limiting Himself to bodily form. Why would He do this? If we had not been created, it would not have been necessary. Why did He create us?
While we can never fully answer the question, it helps to recognize that the answer will come only as we recognize the character and attributes of God. First and foremost, God is a God of love, and love must be demonstrated by showering it upon the object of that love. His grace comes only to those who deserve punishment, and the demonstration of His love and grace and mercy stands without parallel among humans.
But in His love He desired reciprocal love, so He created man in His own image. Man was given the ability to respond to God's love or reject it. In the beginning man enjoyed full fellowship with God, but soon rejected Him, bringing the ruination of all creation. This wasn't God's intention, so He implemented His plan for creation to fulfill its intended purpose.
Perhaps the grandest statement of His purpose can be found in Revelation 4:11, where we see heavenly beings gather in His praise, saying, "Thou art worthy, O Lord, to receive glory and honor and power: for thou hast created all things, and for thy pleasure they are and were created." And there we have it! God created us for His pleasure, for His ultimate good will, because it is best in His estimation.
Unfortunately, the present world with sin and its penalty permeating all things and processes, temporarily experiences postponement of His ultimate plan, but it will not be forever thwarted. There will be the "new heavens and a new earth, wherein dwelleth righteousness" (II Peter 3:13) once again. This is His plan, purpose, and pleasure.
Thus, it makes sense that He would have created things as stated in Scripture, in an orderly, rapid fashion. He would not have used billions of years to create in His image, and He certainly would not have used death, pain, extinction, and survival of the fittest. These are the results of sin and bring Him no pleasure at all.