Mages shouldn't be allowed to wreck structures
OK, I got the Ziggs 6.9 demolition joke being a reality, but that's justified by his theme. However, by auto-atacking all mages deal extra damage to the turrets based on their AP. It makes no sense, both thematically and functionally, auto attacks are considered physical damage, mages' auto attacks are not magical all of a sudden, and should by no means be enhanced by magic penetration.