Saying that we're "setting ourselves up for pain" is a way of pretending that the requesters are doing something different than everyone else (which we're not)
I want to start by stressing that I want birds as much as you do. We played without birds in ZT2 for years and when they got modded in, as good as they were, they were always going to be an approximation of what birds are because we were so limited in what the game could do. The chance of having these animals in a zoo game that is miles ahead of the last zoo game I played is something I want more than anything.
However, I do disagree with what you're saying above because of what you said here below, and for me that sums it up in general.
I tell myself that the walk through exhibits are clearly building up to birds. (Which I absolutely believe). But I can't help but feel that even with that we're being trolled a little bit compared to other rollouts.
I feel like people want birds so bad, that the only possible reason they see why Frontier added the walk through exhibit is because they're building up to birds and almost refuse to even acknowledge the possibility that it was added because they wanted to add bats and butterflies for these two DLCs. It genuinely feels as if people simply cannot imagine that Frontier would add a new exhibit type just for these animals, but it might just very well be that. Because honestly, it really wouldn't be the first time Frontier does something like this.
You can already see it in other places as well, we have our first multi-species exhibit now and people are already jumping up and down again that that for sure has to mean that birds are the next step. But that again might just be because Frontier wanted to add butterfly houses and knew that butterfly houses house more than just one species of butterfly; hence they added that option. It again might very well just be added for that reason alone.
This might not be fun to think about, but there could be a whole myriad of reasons why Frontier might not be adding flying birds. There could be technical reasons why, they might have contractual obligations to other titles they have in the works that mean they can't bring enough people in the PZ team to face the challenge of animating several different species of birds, etc. I don't know the reason why we haven't seen them in the game either, but I prefer to think that I myself simply can't think of the reason instead of there not being an actual reason.
I just think it's important to realize that Frontier isn't trolling you. There isn't an "evil plan" (I know you don't mean it that way, but just in general) here where they're purposely holding back on birds just to mess with us. They might just still be working on it; but they might just not be at all because of reasons they have.
But as long as people are going to assume that the only possible reason walk through exhibits were added was to build up to birds, they're setting themselves up for pain. Because there really still is a very perfectly possible chance that it never was their intention. That it was just to add bats and butterflies. And as long as people can't accept that that's an option, they're going to keep expecting that the next DLC will be a birds pack or the next DLC will "for sure" include a bird, and they're going to keep being disappointed when it's not the case.
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Now, after my feathery "rant" is over, my opinion on the pack
After the stream I was pretty convinced we were going to get a Grasslands pack, and I already had a list of animals I really wanted. Maned wolf, Bennet's wallaby, rhea/emu were the animals that I desperately hoped for and to see that all of them were added I'm just super hyped. I wasn't specifically looking forward or in need of a Caracal, but I'm not mad about them being added either, they are a cool addition.
Butterflies were a nice surprise, but they honestly felt like they were the ideal walk through exhibit animal. They're small and when you look at them in real life they pretty much don't do anything but fly around in circles and little loops so I feel they work perfect for the exhibit setup we have in the game. They're a nice addition, my only criticism I have with them is that I wish the exhibit didn't have to be 8m high for them as well, but from the screenshots it seems like it will be the case again. I feel like 6m high options should be included as well.
Now, the striped hyena and the blue wildebeest are not animals I'm mad about really, but I would have switched them with different animals. If I could only switch one, I'd just switch the wildebeest with an eland and then I feel the hyena in itself is a good addition as well. Ah well, I don't mind these really, the other animal choices are so good that I'm really hyped about this pack.
Looking back at the past year, as a zoo nerd I am overall quite satisfied with what we got. Capybara, Amur Leopard, Manded Wolf, Bennet's Wallaby,Nine-banded Armadillo, Emu, Przewalski's Horse, Siamang, Common Wombat, Platypus and Asian Small-clawed Otter were all zoo animals that I personally have been wanting in this game for ages, and to see all of them added to the game is a pure delight. Along the way other animals were added I'm happy to see, like the lechwe, the oryx, the bat and the raccoon.
This past year has further fleshed out the roster of the game and in all honesty, if this ends up being the last DLC we get, then I'm surprisingly satisfied with the roster. Good job Frontier, hopefully we get to see even more next year!