I agree if it's only fed for the owners sake, however i know of a dog who is allergic to animal protein
so has to have a high quality, but vegan diet and he's in wonderful condition, not sure if it's something that would/could affect cats, but at least they are available if any animals do
need them.
I'm veggie myself but the idea of feeding a veggie diet to my animals for no good reason is mind boggling.