Suggestion for towers

Currently towers have a passive called "Reinforced Armor" which makes it gain 200 armor and magic resist when there are no enemy minions in range. I am sure many people have had a moment when they aced the enemy, but they have no minions and they try to take the inhib turret and end up losing their tank. This passive is great, but when a minion shows up it's all over. The tower blows up, then it's GG. My Idea: Reinforced Armor - The tower has "X" armor and magic resist. The tower's armor and magic resist is decreased by "Y" for every minion in its range. Right now if one minion enters the tower range, the enemy team can destroy the tower instantly because one minion got its armor and magic resist down to 0. With this new passive, the larger the number of minions the squishier the towers get. I'm not a balance professional, but I feel like this makes a lot more sense than the current passive. I'm open to other suggestions and constructive criticism!