I've been to several zoos without aquariums.
Me too, but I said "or". I doubt any of us has ever been in a zoo without aquarium, flying birds, or domestic animals area. At its present version,
this zoo simulator doesn't allow us to build any zoo we have ever been.
There are SO MANY Zoo animals, that it is simply impossible to include them all. So there will always be something missing.
I'm not asking for every animal species in zoos. If we get no blackbuck or baboon it's a shame but they aren't THAT different to animals already in the game, you can use a gazelle or a macaque as replacement species or as a base for modding them.
What I'm asking for is not forgetting
whole animal classes that fill entire areas in zoos. We already have bats and butterflies flying in aviaries, is it really too much asking for birds and saying they are missing? We already have turtles and amphibians swimming in water tanks, if they aren't giving us fish is because they don't want to, not because they can't.
Not every single bird and every single fish, just any bird and any fish, so that more species can be easily modded.
As with birds, I gave my point of view. Comparing this with Zoo Tycoon 2 and saying they didn't reach the bare minimum is where I check out, honestly. Like... we get SO many customisation options in Planet Zoo, SO many zoo features, so many more animals, even if groups are lacking. We got animal genetics, colorations, deep added behaviour over time, exceptional graphic....
Well but the customisation options is a staple of Frontier, it's just the same system from Planet Coaster, so it would be nonsense expecting a different and probably worse system for Planet Zoo. And ZT2 already had coloration variants.
I'm sorry, but saying they didn't give us the bare minimum of a decade old game is, in this point, simply insulting to the developers in my ears.
Well that's pretty much the thing, ZT2 is an old game so PZ must obviously have better graphics and some other better things that reflect how much video games have improved in these years. And I must note again that ZT2 was just 3 years after ZT1, and the improvement leap was as big as PZ after 15 years. So better graphics and gameplay is a given. Congratulating the developers for not giving us aged graphics or a worse customisation system than in their previous game is more insulting I think...
But what it shouldn't be expected is cutting content that was present in zoo games two decades ago and that we know it can be made in the current game.
Once again, I'm not asking for dinosaurs, unicorns, every leopard subspecies and a mobile version of the game. I think I'm being reasonable within what we already know the game could do and what previous zoo games achieved. And if
Frontier doesn't want to introduce content that would do wonders for the game and it would be easy for them, I'm not going to cheer them for the business decision and saying I trust them with another 100 bucks of my money for a Planet Zoo 2.
Edit: OMG sorry for the wall text, I didn't want to look that angry Haha Sorry
@Swjosdotschka 
But I wanted to make my point clear.