If an attacking player plays a ball, and it strikes the hand of a defender away from his body, it is a handball. That's the right of it.
Defending players are not allowed to use their arms - deliberately or inadvertantly - to impede a ball through the air. And that is the right of it. For two reasons. The first being it is fair. The second being it is the most clear way to call the rule.
There is a level of arbitrary decision making by a referee in allowing for deliberate or accidental, when it is not goalbound. As with any penalty , any accidental contact away from the body is a spot kick. In the box this is a penalty. If deliberate, the player goes. If it's goalbound, it's always a red. Harry Kewell got red carded in the last world cup for Australia on an extremely tough call (
https://www.youtube.com/watch?v=0Y4fHzmMaWw) but it happens.
What I'm saying is, there is absolutely nothing to 'fix'. An attacker must not be impeded. Defenders have
all the power in football. The rules like this, and the ones from people who whine about so-called 'diving' all exist because without them, attacking players are rendered vulnerable to physical play. These rules are refined to address the things defenders do to defend. Removing the inadvertant hand-ball rule means you can run with your arms out wide all the time and as long as you don't make a play at a ball, it's play on.
I wish more people would stop and think before posting bullshit 'fix' rules in here.