The only diff is the better materials harvest faster. stone axe harvests the same amount off ore/stones as a iron or steel pickaxe or a auger. a bone shiv will get just as much meat/hide/bone as a hunting knife or a machete.
This problem is even made more apparent by how all tools harvest the same amount.
Why its set for 20 damage is beyond me, it makes it completly worthless imo. Probally around 30 base for machete, which puts it higher than iron reinfeced, but lower than sledge. SO I guess the hunting knife being weak is excusable, but it should have at least the same damage as a wooden club, the machete however should have a higher base than the iron reinforced, just because of what its made out of. Hunting knife, yeah I don't see that severing heads, but a machete blade? been lots of movies where you'd see people/monsters being decapatated or otherwise limbs cut off by those. Unless.that blade cuts all the way through their necks.