Similarly I always feel little stitches from rhetoric use of the perceived degree of organicity a thing possesses in contrast to another. It's such a vague metaphor. I guess what usually counts as more organic is: - stuff that decomposes, is not ignored by destruents and stinks - stuff that is complex and semi-random, no central, overall plan

So maybe it's the last point. For an animal you need a thorough layout, like for a cathedral (but, well there are also Gaudí's which aimed to be more "organic" - all these metaphors are so messy, maybe natural language is too organic)