The NPCs are designed in such a way that makes it very easy for players to decipher the services and items they provide at a glance, at least most of them. Outside of having an actual animal as an NPC (which would have been fine), or somehow making the zoologist NPC look like a zookeeper (also fine), I think the fact that the NPC is reminiscent of an animal very much indicates the services she provides. I don't think it was a mistake. Yes, it could have been different, and so could everything else have been different. The chest size also makes no discernible impact on the fanart, because as any seasoned forum-goer or social media follower knows, every single female NPC has had their fair share of fanart.
I would sincerely hope people don't get toxic about it, but it seems like most of the toxicity is raised about the fanart while simultaneously blaming it on the "furry" aspect of the NPC. I believe this is an argument in bad faith, and implies that the "furry" nature of the NPC is why it gets fanart, and not the fact that it's the first new female NPC we've had in quite a while, and is subject to the same treatment that every female NPC has had prior, as is the "controversy" surrounding certain NPCs and the art.
So in short, no, I do not think it was a mistake in the least. I think she's cute, and I think having an anthropomorphic NPC, especially that of a fox-like variety (which is very evocative of nature), is perfectly fine to demonstrate her services.
