Who's saying they're not? It takes a long time for a model to go through the entire process. If you guys are seeing it now, how long ago do you think we started working on it?
I think what we mean is, why this, now? If we want to talk about RP-related features, the game needs alien races to interact with, pirate NPCs with ships to board and crew to battle, and maybe some ship decorations, pilot seats and better multi-person crew mechanics, and so on to make our interiors less dry... Space whales and other planet/space fauna are cute and all, and they'll make for a great addition to spice the universe up a bit if they're not too common, but they don't do much of anything for gameplay and barely do anything for immersion. The new starter station, on the other hand, helps with both, in addition to setting a sort of standard for building quality - but that wasn't even made by the devs. I'd think space whales would be a thing to add later on along with things like Schema temples on planets; silly-but-awesome things to put in when all core features are done.
Why should Schema be working on space whale AI and combat mechanics (i.e. whale nose ramming), Zanaten be working on the space whale animation and models, and Kupu be working on the space whale/other fauna textures, when Schema could be working on a captain's chair system, crew AI and functions (And fixing those bugs like the one where crew members can't even stay aboard your ship), Zanaten on weapon models, interior pieces, and so on, and Kupu on, oh, I don't know, some more crew textures so not all crew members are clones of each other, as well as textures for things like the aforementioned interior pieces? You know, things that would, or at least might, immediately effect what someone regularly sees in their day-to-day interactions with the StarMade universe. Of course, ideally we'd be seeing things like the thrust revamp, faction mechanic extensions, and the like first, but apparently we've moved into some kind of "RP Season" (which is good too) so...
Of course, there's no rolling back time, and I'm sure that by now the devs are probably working on cooking up some other cool stuff we don't even know about yet... So there's nothing left to do but wait and see. Besides, even if space whales, desert ratlings, and other critters are badly-timed, they're still a great addition to the game and would have to get in sometime, and personally, I'm loving the art style and general concept of both creatures.
(This post is assuming that space whales and the fauna AI and model framework are taking up the majority of the devs' time. If this is not so, and Schema is mostly working on new faction systems, 3D-model block support, or something else like that while the art team finishes up the two new fauna demos, then this is completely invalid and you can just ignore it. But I somehow doubt that.)