I can understand where the OP is coming from, to a certain degree. Though this is only one DLC, one that was clearly pushed for a Christmas release, if it is the beginning of a pattern then it doesn't bode well. How can you expect your players to be satisfied with, say, an Australian DLC with four animals, two scenarios, a building set, and nothing else? There's a lot more in Australia than that, absolutely, and if we got, say, the freshwater crocodile or the lace monitor instead of the Tasmanian devil I'd be livid. Already I've seen people suggesting that Frontier might do another Arctic DLC down the line with the animals we actually wanted in it, like the Arctic fox and wolverine, but I don't see that as being likely, and we're all going to feel a little ripped off if they do an animals-only DLC for five or so bucks that includes animals that should have been in the main DLC in the first place (I'm reminded of The Sims 4: Pets and the following My First Pet Stuff - what an utter travesty that was).
That said, I'm neither willing to get my hopes up or willing to make broad assumptions. As I said, this is just the first DLC, pushed for a Christmas release, so it's not a good gauge of what's to come. The next DLC will either create a pattern or surprise us.