Why is the top wishbone at an angle?
 

Why is the top front wishbone at an angle?

Has any one plotted the affect of this as the suspension moves through its range?

Is it to increase caster under suspension compression and add stability on the brakes?

Anti dive. As you apply the brakes, that torque load in transferred into the arm. This causes a downward force on the arms, preventing the nose from hitting the ground.