Bring back +5 bonus AA damage to Minions; adjusting Turret damage is a poor band-aid fix
Turrets doing 45% instead of 43% only solves a small subset of the overall problem, which is CS'ing full-HP melee minions under the tower. It's not going to solve Anivia trying to CS a Caster that's being focused on by 3 melees and a cannon. In fact, turrets doing 45% will make it HARDER to CS if the minion's HP is within certain ranges, such as 85%-90% and 43-45%. Granted, those ranges are not a big problem, but the overall turret damage change is clearly inferior to just having +5 damage vs minions.
The original mechanic was fine, there is no reason to remove it and put something clearly inferior in its place.