Difficulty clicking on the correct object
I think the screenshot below will be sufficient:
I'm clearly pointing to the corpse but the game still picks the dying Firebreather. And this happens way too much, much more often than in DKII, and not only with dying/dead units, but with alive as well.
Hm? You still can't pickup dying creatures, so why would they have priority over corpses? It makes checking who died a tremendous task unnecessarily.
The answer is quite simple: Dying minions can be rescued by your workers, which either will bring them to your lair (if they are your own minions) or into your prison (if they are enemy minions).
Dead creatures, however, can only be used to raise ghouls, which are much weaker than living units. Therefore, unconscious/dying/KO'd minions have priority over corpses.