Well, I think we can all agree that sterotypes and over-the-top characters have absolutely no place in the WH40k setting…
We all play this setting for deep explorations of the human condition, our characters having complex inner worlds which we develop over the course of the campaign with complete psychological verisimilitude. Who here could have read any of Tolken's novels without throwing them away in disgust at the cardboard characters presented? No one of course.
The inappropriateness of Ratlings within the setting is self-evident.