The field goal comes from the fact that football is loosely based on Rugby. Which has a designated kicker try to kick the ball thru the up rights from where the ball was crossed over the goal line. It gets get brought back a bit, (I forget how much) but the hash mark so to speak is where the ball went into the endzone. So Rugby players want to enter the endzone in the center of the field, which then makes it harder because the defense knows this as well.