I don't think it's a "bait and switch" to portray animated characters in a different art style in the promotional material than in the show itself. Heck, the opening titles of Batman: The Animated Series
show Batman as a still painting (or mostly so) in a couple of places, which is very different from the style in which he's rendered in the show proper. It's no different from a comic book having a photorealistic, painted Alex Ross cover and more conventional line art inside. Or a live-action movie being promoted with a painted poster rather than a photo-montage one.