Just a thought for Necromancy skills and if the summon undead *would* require bodies:
They could add in a second skill that would be able to target those ash piles/heavily damaged corpses, and instead of summoning a zombie/skellington, summon some form of spirit/ghost.
When I think of Necromancy, I think of undead, blood magic, hexes and curses, and bone-based spells, like Necromancers are typically attributed to. I honestly was hoping for more undead summons in D:OS, but thankfully that's not why I bought the game, and I really enjoy it. The change of name from Witchcraft to Necromancy originally confused me a bit, as I had gotten used to the name, but here's hoping they changed the name for a long-run goal, and are going to be adding in the more 'traditional' Necromantic skills, summons, and spells.
Still waiting and hoping for the day that I can finally raise an undead army in a game, force them to build me a castle, and then live out my days in a palace of bones and blood. Such is the dream.