Which then begs the question - why not simply command the heart to tear itself from the chest? Or head to tear itself from the shoulders?
Why not animate all the body parts from a recent battlefield into a giant flesh golem? Or assorted tins, pans and pot into a walking metal monster?
Take for example the "you can't see the heart". Fine. But I can see the head. So why not rip the head off insted of the arm? So as you can see, you have to pay attention to explanations and the workings of magic.
He is talking about the gameplay of the spell, and you are only thinking the mechanics of the spell.
Yes, it is a very unbalanced spell. Even without ripping hearts or heads, ripping someone's hand can make him die or suffer terribly. In reality, if you rip someone's hand, it will cause huge pain that can faint the person. Even then, his wrist will start to bleed, and it can kill the person quickly.
The spell tries to combine these two issues with "6d6" but of course it is not enough. Even worse, the hand becomes as powerful as a Wight and start attacking the person.
And this is a level 4 spell.
But forget the power, forget the mechanics, he is trying to explain that he wants more than "fireball, lightning bolt, icebolt, firewall" type of spells, more alternative style magics.
Of course, I am happy with spamming fire spells