yes, there's a reason. moving the pivot upwards will alter the angle of the LCA relative to the tie rod. This will mean they will travel though different arcs as the suspension moves and it WILL cause bump steer.

better way to 'correct' the angle of the LCA is to fit a spacer between the strut and steering arm, which moves both the LCA and the tie rod at the same time.

Or just don't lower it so far...

This so-called correction of LCA angle is really a roll centre adjustment.