In the end I can imagine you're thinking, "Well, then why bother?" in terms of what Aquinas was referring to, God bothered because he could only accept authentic love. After all, God is all that is true and good. God does not need us, but if we are to assume that God is all that is true and good, why should we assume he would accept anything less? (However, I guess this is resolved in the new testament?) In the case of Christianity, we inevitably end up returning to the issue of choice and God's love. In order to know love and to love, you must first be conscious
of this idea of love. Second, you must choose to believe and live by it. "Evil" is when Man, who is free, does not wish to be with God or know God (all that is good).