If you try this simple exercise it may help to illustrate why playing for a particular shot shape is 'easier' to work with.
Take a soccer ball and try and hit a firm straight shot at a target say 20 ft away. To keep it straight you'll have to hit it with the top of the foot, not either side.
Try it 10 times or so.
Now try and hit the target with a slight draw using the inside of the foot. The results should be that you will get more on target and, if you try and do it with any type of power, the ones that miss will be closer, and more predictable. The attempted straight shots can go all over the place.
My kids used to think it was amazing when they curled a soccer ball. Doing this once, showed them hitting a straight shot is much much harder.