Ok some electrical stuff...
Back many years ago Copper was.. Rationd and even aluminum was costly so the power companies did a "Single wire" delivery system. Basically they ran one wire from the pole to your house (How did that worK? you ask) the other "Wire" was the ground earth ground was the "Return path" Well Some systems to this day work like that. Though most new installs are 2 or 3 wire (Hot/neutral 120 or hot/neutral/hot 120/240 or multi-phase industrial but that you won't likely find in a house)
However the ground as a return path STILL EXISTS both at the pole and at the service entery (near the meter).
So what happens if you plug in say a SKILL hand grainder (like a dermel but industrial size) and there is a Hot to Case Short?
IN my case the thing had a tendency to leave my hands.. VIOLENTLY. but that's because of the nature of my muscle development (more attuned to throwing at that time) most folks are more attuned to lifting and will clutch) and you end up dead.
(Why I bought my first dremel)
The GFCI is designed to cut off current if that happens before you even feel a tingle.
YOu've seen the classic murder mystery where the killer tosses a hair dryer into the bath tub. or a TV.. Well with a GFCI. The victim lives and the killer goes to prison cause NO POWER before the vic can even feel a tingle.
I WOULD NOT REPLACE THE GFCI WITH A STANDARD OUTLET for that is the way to an early celebration of your life called a Funeral.
And when I go to my funeral I hope to be as "late" as I possibly can be (Take that both ways).