The problem with not going over the top, then playing it straight, is that the Abnormals premise is already silly. It's very much like SG1 that way. It's just not possible to start with such nonsense then pretend it's all serious. For my part, Sanctuary realizes this, goes over the top to entertain us, the audience, while the characters take it seriously. For the characters to show their tongues in their cheeks, well, you can't speak clearly while you're making a face.