> - already exactly know where you want to go

Same as with moving down by 1x10? How are you even choosing cursor direction if you don't know where to go to?

> - figure out the relative distance either by looking to the side

Ok, how is that an issue? You also have to figure out the distance by looking down when moving down with the arrows, so eyes still move?

> move your hands to the numbers row to input numbers and back

No, you could maintain your hands on the home row and use a numpad layer containing it

> imagine you had to tell your hand "move 10 centimeters left"

Imagine you had to tell your hand "move 1 centimeter left 10 times"? The mouse is that extension where you don't "move by 1 pixel X times" and move in an analog way