They just did that to replicate the factory upper control arm ball joint angle. It just keeps the ball joint sleeve closer to perpendicular from the spindle at ride height. Some compensation for the tilt the anti dive angle put on the upper control arm.
Nothing to lose sweat over, IMHO.
It really doesn't matter. Because that angle from the side view doesn't change enough to over extending the angle of the ball joint stud to the sleeve. That angle doesnt change much at all. And an upper ball joint tilted a little is fine. That why it's a ball joint.