My motor game is weaker than it should be for my profession, but I think that's basically right. A DC motor without permanent magnets are switched or variable reluctance. They require some decently complicated control circuitry (wasted power and space and weight) and are kind of loud, which is bad for hiding things.
You could use a synchronous motor or similar, but they're large, heavy, and need AC power, so you'll waste a decent bit of power (and space) on a large inverter.