Excellent analysis. Why was the temple veil torn from top to bottom?
There are two ways of answering this so I will do my best to answer both.
1) It is a traditional Jewish sign of grief or mourning. It is called the Kriah (Kree-AH).
Genesis 37:34 34 Then Jacob tore his garments, put sackcloth on his loins, and mourned his son many days.
2 Samuel 1:11 David seized his garments and tore them, and so did all the men who were with him.
The second was so that no one could say that man/men had done it. It could have been done by several men, making a cut in the middle of the bottom and then pulling on the lower corners. Being done fro9m the top to the bottom, it had to be done by God.