The whole sweep and flow of the Old Testament with it's types and symbols demanded that the Messiah, the Lord's anointed, die for the sins of a world that could never itself atone for those sins. The death of Christ has been called the scarlet thread of scripture, the supreme truth around which all others are woven.
John MacArthur, Matthew 16-23, P222
If MacArthur is right, and i believe he is, then this has a huge bearing on how we read the Old Testament. We should read it with the understanding that Jesus wasn't lying in Luke 24, with the understanding that we are not the main character.
Genesis 22 isn't God telling us that we need to be prepared to sacrifice anything and everything, but a picture of the cross.
Exodus 12 isn't just interesting dinner planning strategy, but (another) picture of the cross.
Joshua leading Israel into the promised land isn't about how we overcome opposition, it's about how Jesus destroys God's enemies.
Boaz isn't supposed to show us how to welcome people that are different from us, but how Jesus us our kinsmen redeemer.
Judges 11 isn't about baby dedication, it's about how desperately Israel needs a judge who wasn't A) nuts B) mortal.
We need this Jesus, the sixty six book Jesus. We need to show non Christians that the Gospel isn't something that was made up and stuck onto Judaism, but that he had been expected for generations. If Moses and Abraham knew (in a non wholly reveled way) about Jesus, how could anyone believe that the disciples made Him up.
The Old Testament is rich, and it's full of Jesus. We lose so much if we ignore it, or worse, try to make it about us.