The only change towers need

Towers gain bonus 200 armor and magic resistance when no enemy minions are nearby. --> Towers gain bonus 200 armor and magic resistance and give allied champions bonus 50 armor and magic resistance when no enemy minions are nearby.

Complaints about towers include them not protecting us well enough, that it's too easy to dive someone.

There are various problems with increasing damage such as making armor less useful (Tanks SHOULD be able to tank towers for a while) and messing up CSing.

Towers need to protect us just as we protect them. This rule should exist throughout the game, though more early game than late game. Diving should be a possibility, but not commonplace. If we protect the towers by clearing minions out, they should protect us in turn.