There's a lot of objectives in the game now.
Dragons matter more now since they give stat buffs and not just straight up gold.
Rift Herald Exists, and First turret is pretty important.
The reason these changes were made was to solidify game length. Too many people complained about games going to 50 minutes too often. The ideal game length to people on the boards was 30 minutes. Maybe a little less.
The side effect of this is that the winning team has more options to close out the game.
Riot's mitigating this by buffing shut down gold so comebacks still happen, but in high elo, unless the winning team absolutely fucks up they're most likely going to win.