So, just to be clear, a foot of height difference is very different in physical movement in humans. A person who is 5 foot 6 is at a severe disadvantage kickboxing against a person who is 6 foot 6, assuming equal training and skill. The taller person will also have an easier time clearing distance quickly, clearing low walls without slowing, finding someone in a crowd of people, and a harder time fitting into tight spaces, and hiding.
It's not a small difference.
All that being said, the idea isn't to go foot by foot, the idea is to say that if you choose to make your character especially tall or short, the gameplay will sometimes reflect that, usually in terms of opportunities you will have to leverage that description when attempting to accomplish various tasks. I've a teenage character in a star wars game who is 4 foot 6. She has a much easier time finding places to try to hide than the other human character who is over 6 foot tall. No bonus or penalty to any rolls involved, just the fiction being...affected by the fiction. Which seems pretty obvious, to me.