True. Sometimes they are cast as the protectors of the mice, though (Tom and Jerry, and the dog in Cinderella, come to mind), which would probably be less acceptable if it was assumed that they were planning to do to the cats what the cats were planning to do to the mice.
Someday, I want to own a cat that looks like Dream in his cat-form. I imagine waking up in the middle of the night, with that coal-black form sitting over me, glaring down with those smoldering crimson eyes...best pet ever. For, you know, producing fear-borne aneurysms.