Inhibitor and nexus turrets should be lasers to save the game
The outcry on the boards has led me to investigate what has affected the game significantly enough for the overall consensus that league is a dying game. Back in 6.22, Riot changed the inhibitor and nexus turrets to shoot bullets instead of melting with lasers. There was a dramatic shift in the length of game time and I think it was due to the turret changes (not counting rift being easier to take). This would be a great step to allow teams the proper chance to win from behind. I do not think this only the change though.
We are in a meta where whoever hits first wins. If this can be reduced in some fashion, I think league will go back to an earlier version of itself that was more enjoyable to players, unfortunately I do not have an answer on how to correct that problem. I would assume it would lie in the items and/or runes.