Creep aggro is probably one of the most, if not the most important thing in the laning stage. If a player with excellent creep aggro skills lanes against someone who was only mediocre at it, he would completely dominate the opponent player no matter what heroes they play most of the time.
This is because creep aggro controls the pace of the game in the laning phase, and using it properly can gain you alot of benefits such as: Leading the opponent to somewhere they don’t want to be. Controlling the creeps to go where you want them to (eg: Nearer to your tower), can bait the opponents into walking somewhere unsafe for them. This would obviously lead you to be in a position in which you are more likely to kill the opponent.
Next, it will deny the opponents of gaining control of the lane. If you are playing mid, gaining advantage over creep aggro may mean luring the creeps nearer to you and your tower rather than your opponent’s. If played with a range hero, it can be disastrous for the opponent as he/she won’t be able to trade hits properly, due to the highground missrate. Which will of course destroy the opponent’s laning phase.