In my understanding, it explains to me why God created. If God is simple as you suggest, with no real distinction in Persons, if He is closer to the God of Islam, then I simply cannot understand (perhaps this is a product of my own stupidity) why He created to begin with. For God is perfect, lacking nothing at all, and had nothing to achieve or perfect in creating. But like Romano Guardini says in his work The Lord , love does these things. We believe God is Love, that He freely chose to give Himself to us, in our very act of participating in some measure in His being (which extends to all of creation in varying degrees). God’s inner nature of Love among His three Persons, His being eternally in love with Himself, that He is Love, this explains to me why I exist–for love does these things. Sometimes I find myself doubting whether I have reconciled what you are struggling with, for it is a great and difficult subject and I am little and simple. But then I keep coming back to why am I here, why was I made at all. And when I look at Aristotle and Plato, I see them unable to explain how the Prime Mover or the God of the Forms makes contact with creation, to say nothing as to why. Maybe you have a reason why a God who lives in isolation, who therefore cannot be said to be Love, creates. But any one I have seen is more a problem to the truth of Divine Simplicity than the Trinity–the Trinity reconciles, for me, Divine Simplicity and creation.