Many of us like to limit our water usage now that we live in more water conscious times. But keeping the water level low in your top loading washer is not the place to make those savings as you are likely to have to buy a new agitator.
One of the commonest parts we replace in washing machines is the agitator. This is because the fins break. They are not made very robustly, but that may be to protect the motor of the machine; after all if the fins are robust and the motor has to work very hard, it will fail faster than if it has an easy life. So instead, the fins break and we see many people come in a buy a nice shiny new agitator. Our advice always to them, is keep the washer on a high water level unless there are only a very few pieces of clothing in there to wash, because a load of washing in a full washer is much lighter than a load of washing in a half full washer.
Think of it like a bowl of soup. Stirring a thick minestrone will meet resistance, because it is full of vegetables and pasta. Keep your washing machine water at a miso soup consistency though and you will probably never have the pleasure or the pain of having to buy a new agitator.