Base towers are entirely too weak (or death timers too long)

Lane towers at least feel like a threat at the start of the game, and it often takes a while until you can take on the second one, but when you reach that point the remaining towers feel even weaker.

For example when you take down the second tower and kill some of the defenders around minute 25 you often can destroy the Nexus before they have fully respawned. That's the entire base defenses destroyed in less than a minute.

A single good teamfight at the second defense line should certainly give you a good advantage like maybe the inhibitor, but it certainly shouldn't instantly win you the game.