I think that Dark Energon would probably work better if it created vampires and not zombies. After all, vampires trump zombies; a sentient undead warrior is better than a brain-dead monster. There’d have been more mileage for Cliffjumper, with him being some kind of vampire/dhampyr struggling with himself over what to do. And look at how dangerous Airachnid became when infused with Dark Energon. And it’d have meant making Megatron a vampire overlord. Which you have to admit would be awesome, by itself and in making him the counterpart of Optimus Prime who holds Primus’s lineage. It’d be like something from Castlevania. So yeah, a probable missed opportunity there with that concept.