God’s motivation is really quite understandable, and purpose for our lives, if you belong to him, is also intimately involved in it: joy for himself in our love for him and our pride in him as our Father, and joy in us and joy for us in reciprocated familial love.
The original unfallen creation was merely ‘very good’, not perfect:
God’s purpose was and still is to magnify the most valuable thing there is, namely himself (he would be lying if he said otherwise), and to increase and share his joy. He is happy in himself.¹
Father’s intended purpose in creating the world was to was not to create a ‘perfect’ one. His purpose was not thwarted. Since it was a two creations model² from the get-go, the first one was subjected to futility on purpose, from its very start and before death occurred.
The original unfallen creation was merely “very good”, not perfect, since it did not and could not magnify God’s justice, mercy, grace and love through our Lord, Jesus, the Christ. Jesus’ motivation is also explicit and clear, and it was forward looking³: “for the joy that was set before him endured the cross, despising the shame.” Hebrews 12:2. That joy is us(!), if you have been adopted into his family.
The New Earth will be perfect.
¹ See The Pleasures of God.
² “Then the King will say to those on his right, ‘Come, you who are blessed by my Father, inherit the kingdom prepared for you from the foundation of the world.” Matthew 25:34
³ Our motivation should be forward looking, too, toward future grace. See Future Grace.