The problem with this game is that the developers went all "IT'S PROCEDURALY MADE" and failed to account for the million flaws such a system has. The code does not account for: Gravity, Environment, Predation, Diet, Evolution...
You never see a procedural video game even try to make animals look like they have a common ancestry from which they split into Phylium or division, subphylium, superclass, clade, family, species, etc.
Due to different mutations that adapted them to gravity (having six legs or a really strong tail and two legs), environment (ex: water sacs in their bodies or four stomachs), food (Carnivore, herbivore, omnivore...) and vestigial traits from their predecessors. Some animals develop better muscles to run away from predators, others develop claws to climb trees or cave ceilings where they are relatively safe... until a predator develops a counter-response.
There simply won't be a code-made game that accounts for that on the fly because the devs go for one thing: Make it cool and cheap. It's never made with love and care.
To be fair, from a programming standpoint, this would be immensely complex to implement, perhaps prohibitively. It's basically a simulated evolutionary biology engine, something that would be groundbreaking in its own right as a scientific tool. I wouldn't expect something like this to exist with any kind of accuracy within 5, maybe even 10 years.
It's one thing to even program it, but it also has to procedurally render the resulting creatures accurately according to the parameters that are calculated by the evolution algorithms. We know this is possible, but doing it well is a very different story. When designing a game, you do what you can with what you have first and foremost. Then you iterate and over time these more advanced aspirations become doable as tech and practice progresses.
Remember Spore? It originally had the lofty aim of doing almost exactly this, if not to as fine a detail level as you're probably thinking. Instead, it delivered Penis Creature Studio. And that wasn't even a game trying to also be a seamless space exploration sim (well, maybe in its very earliest rumors, but that died off quickly IIRC).
I haven't played No Man's Sky, but will probably check it out in several years when it's cheap, my system is more than capable of running it, and there are (hopefully) interesting mods for it. Most new games are relatively **** at release compared to how they mature with age if the support is good and they have modding accessibility.