it's not natural, but it's convenient and balanced. (a human equivalent product of a dry dog/cat food would be brilliant, instant balanced diet - i know i'd eat it! save time and it'd probably make the weekly shop a damn sight cheaper too.)
variety is good for dogs, we had an older collie who was a really fussy eater, so we gave her all sorts through her life and her meals were always different (the only constant thing she god was her dinner, tinned beef slices in gravy with some weetabix and mashed vegetables mixed in, and a bowl of bakers biscuits being left down on an evening for if she fancied some "crunch")
her evening meals were cooked by me though (she was a fussy hound, remember.) cycled through lamb/pig/and beef heart, diced and boiled with pasta/rice and some vegetables, or kidney/liver done in the same manner.
she'd every so often just have some microwaved fish and rice. and she only ever ate something out of the street once.
where as our other dog would eat a dry food and was quite happy with that (though his evening meal was replaced with whatever the first dog was having most nights so we didn't feel so guilty) since the older dog passed away, he doesn't get that meal on an evening any more - instead he has his dry food
he's started picking bits up in the street now. not all the time, only on the odd occasion. really don't like him doing it, but i'm not going to be cooking for him every night for the rest of his days as well. (he still gets it as the odd treat once in a blue moon mind)
something i don't understand is cat foods with carrot and other vegetables in them... what benefit is there of that?!
it just sails right out the other end of the cat. purely there to entice the owner.