Yeah, I think with a lot of characters with Beast modes, like Grimlock, Sharkticons, etc; the Beast mode is their true form, while the purpose of the android mode is more for social interaction. Gnaw is basically a hungry beast who's only loyal to the last person who fed him, and I think that behavior is more fitting for an animal than a person (not to insult Gnaw). I like this because it creates diversity among the types of characters we see in Transformers.