Th' soul is where th' humanity is. Compassion, your bleedin' conscience... all th' lit'le gooey stuff that makes humans human. Without it, there's no remorse. No regret. You can do whatever you bloody well want and not feel bad about it for a second.
Angel didn't choose to get his soul back. He was cursed with it... centuries of ill deeds and then he was doomed to repent for it for all eternity. Every shred of guilt, every sliver of remorse... [ Pause to let that sink in. ] It's not pretty.