You know, maybe the problem with exhibit animals is that one per pack never felt like enough... Especially knowing Frontier's uhm.... "Questionable" track record with them.
Usually, DLCs add the more iconic or representative habitat animals of a given region or biome, often including the big ticket sellers; having 4-7 animals also helps in offering something for everyone. For example:
• South America Pack had the jaguar, anteater, llama, and capuchin (though any monkey would have been good; South America just needed a monkey in its lineup; Capuchins are perhaps the most well-known or even the most "generic").
• Southeast Asia, our first animal pack, had somewhat more obscure critters, but still kind of known by the general public: the "human in a bear costume" (which, being a bear, is a great selling point to the average person), "nose monkey", "self-impaling pig" and the like.
• Africa had the rhino, meerkat, fennec fox, and penguin. Basically zoo essentials
• Oceania had all the iconic Oceanian animals we were still missing, plus the quokka... Which is definitely not an obscure animal with its huge internet fame.
With exhibit animals though... You just never know. There are a LOT of heavy hitters that could fit into a Planet Zoo exhibit, animals that definitely work for the exhibit format without any modifications... And yet, most of the time we end up getting random bugs or small critters that are often far from what the fans have asked for. Also, having only one exhibit animal significantly lowers the chances of satisfying everyone's demands. Let me give a few examples of what I mean:
• South America Pack could have included anything: the first animal that comes to mind is the Green Anaconda, a true icon of the Amazon river basin; it's large enough to be noticeable in a 4mx4m exhibit - perhaps even too large. Well, then any turtle, lizard (Basilisk?), or snake could have worked... And instead we got the Red-Eyed Tree Frog. Fair enough, frogs are fairly representative of the Amazon, and the Red-Eyed Tree Frog definitely stands out from the two other Amazon frogs we had.
• Southeast Asia could have finally brought us the long-awaited cobra, an animal nearly everyone has been unanimously asking for since base game; it even had its own statue in the India set... But no, we got the leaf insect. Sure, it's fine, but it's not really what most people wanted or expected from Southeast Asia, which is notorious for its snake diversity (pythons, cobras, vipers...)
• Africa is in a similar situation... The Black Mamba would have been a perfect inclusion, and a cobra would have worked perfectly with the North Africa theme; the addition of a chameleon would have brought another heavily requested animal to the game... But no, we got the dung beetle. It works perfectly with the theme of the pieces and it has very unique features, coming with its own custom exhibit and dung rolling animations, but again: it's not exactly what most people want or expect.
• Oceania had even more options: since the walkthrough exhibit was introduced less than a year ago, the possibilities were endless. We could have gotten the (slightly infamous) Lord Howe Island Stick Insect, which was rejected from the Australia Pack; we could have gotten the Tuatara, adding to the New Zealand representation; we could have gotten more butterflies from New Guinea and the like; we could have gotten a new Australian critter, like a snake or a lizard; we could have gotten birds...? But no, we got a bat. It's not the end of the world, flying foxes as a whole are widespread in Oceania with a huge variety of species... But we got the spectacled flying fox, which has virtually no captive presence, is incredibly obscure, and isn't even all that suited for a walkthrough exhibit in real life (that's what a few Australian people told me, but that's besides the point).
In the end, I feel like this attitude of Frontier towards exhibit animals is based on the (often true) assumption that nobody will care too much about exhibits. You just plop down the box, throw in the animals and call it a day. Still, having two exhibits per pack would have increased our exhibit roster while adding more representation to each biome/region, and at the same time it would have allowed for some heavily requested animals to finally make their way into the roster without necessarily having to sacrifice the weird bugs and critters.
[TLDR: bugs cool but snakes cooler. 2 exhibits per pack better]
Aww and they gave them a sitting animation.