Turret balance idea?

What if the tower gains additional Armor if there isn't an allied Champion protecting it? That way, even if you're killed there's still hope that your tower won't be taken down pre-6. Just a random idea.

EDIT: There was another idea I thought of where your opponent's tower gains Armor Penetration based on how much damage you can do, where it would reach a certain maximum Penetration based on the combined Levels of each opponent Champion. Then I thought: what if there was an item that would let you convert Armor Penetration and damage to Armor, and vice-versa? A toggle-able item with 3 settings that would cost (Mana, Health, etc?) that would let you switch towers between offensive, defensive, and balanced stats? Just a thought.