The motivations for a villain, which I think is a good idea, shouldn't be tied to their ability/origin. Like Tal_N said, Freakshow are technological/science based, but like to cause chaos.
How a villain gets their powers might be different from their motivations to be villainous.
I don't particularly like the 'Power' motivation you have, as you've categorized it. I don't see why it would have to be through magic only.
And what about the unethical pursuit of knowledge (magical and scientific)? Dr Frankenstein and perhaps Doctor Octavius?
I think it would be good if our characters could choose a villainous motivation, though. Good thinkin'.
