Most gloves are so padded that they extend anywhere from one to three inches from your fist. This will make your strikes come up short when you take off your gloves as you'll be more used to their striking distance.
4. A gloved fist doesn’t cause damage the same way a bare fist does.
Most strikes with a glove are spread out equally on it's surface but with a fist it is more compact so the impact force is more solid. And a barefist can get into areas that a glove can't.
In other words it hurts more getting hit with a bare fist.