Yes. The crits. But you will be spending less time dodging and more dpsing with the legendary amulet, when you have hardened bones on it. And you will get stuff like coalesced blood and primary stat on it plus the tempers.
Edit
But dunno man. I can push 90s with blood surge, but the single target damage is so low, that the bosses feel really annoying and slow. I think i will switch back to blight, even that bs is way more fun. Only if there was a solution to single target damage with bs in earlier iteration of the game. Oh yeah there IS. Funerary Pick in D3.