Yeah, but the ones we'll see the most of are the most humanlike, and with only fairly minor variations from the human form, like pale skin and eyes, hairlessness, or the subtly feline brow of the Irathient. Other shows have at least had more creative prosthetic designs for humanoid aliens. The Irathient makeup is a good design as far as it goes, but I just don't like aliens to look too human.
I'm not crazy about some of the names either. The Castithans are caste-based, and the Irathients are aggressive (as in wrathful)? Isn't that a little too on-the-nose?