Besides the beginner problem, there is the cheater problem: if you call double hits on yourself or your arm hair touching a ball when bridging over the ball (I tend to feel that regularly) is your opponent going to do the same thing? In my experience, the answer is "no". I've played people in tournaments where the cue ball only fouls was in effect, and they clearly double hit the cue ball, and from their immediate reaction I knew that they knew they double hit the ball, but they quickly recomposed themselves and walked to the next shot as if nothing untoward happened. Under the new all ball fouls rule for all games at all times, those players are never going to call their shirt touching a ball or their arm hair touching a ball.
Personally, I think the ball should have to move for it to be a foul: if your shirt are arm hair barely touches a ball what's the harm to the game? For the layout of the balls, a light touch cannot be distinguished from no touch, so nothing is different.