Why did Jesus have to die?

The Bible and traditional Christian theology tell us that Jesus had to die because humanity was lost in original sin. Jesus' death and resurrection paid the price that we would have had to pay for our sins, and all we have to do is truly accept his gift.

First let us set up some definitions.

God: Omniscient, Omnipotent, Non-Temporally bound being who created all things.
Jesus: Emanuel (God with us), Son of God and also God himself. See the Gospel of John chapter 1.
Humanity: Creations of God, originally good, but defiled by our original sin through Adam and Eve.

I recently re-read the story of the drawbridge operator who sacrificed his son to save the lives of those on the train.

The Drawbridge Keeper

I'm sure it's not a true story, but it can be moving nonetheless. It's usually told as an allegory for God having to sacrifice Jesus in order to save us all. The major problem as pointed out in the above link, is that Jesus' death was not an accident and that is where it breaks down as an allegory. This story made me think of another problem, but it's a problem with both stories.

God is, as stated above, an omniscient, omnipotent, non-temporally bound being who created all things. I guess this ties into the first problem. Before god had even created Adam and Eve he knew that Jesus would have to die on the cross to redeem all of humanity. He knew about all of the atrocities, all the suffering, and all the pain that his children, all of us, not just Jesus, would suffer.

Why did it have to happen? Essentially, it looks like God set Adam and Eve up to fail.

Why? I don't have an answer, but I'd sure like one. It is to that end that all of my non-intercessory prayer will go.