This happens with other cosmetics too, but take this examplo:
Karrum-Class Rebreather with Augmetic Eye Implant
The eye implant is available for all 3 human classes. (Spectrus VI model bionic eye)
The Mask is available only for the Zealot. (Adacore Rebreather)
Both the mask and the eye implant is available only for the Psyker. (Karrum-Class Rebreather with Augmetic Eye Implant )
What is the logic behind this? Why not make it available (Mask+eye) for all 3 at once?
the logic is simple: if you arbitrarily limit cosmetics which could logically be able to be worn by any human class, you increase your odds of pissing off your player base unnecessarily by monetizing said cosmetics in a way that is wholly antagonistic to consumers.
What they’re seemingly going for is in-lore hijinks with the Psyker being limited and having to wear that collar / pack / helmet thing.
Only problem is it’s not fully consistent. The extra-ordinary gear from the cosmetic shop has broken the in-lore suspension of disbelief a long time ago regardless. So the limitation feels like a shallow husk of what once was. Some people like you OP can’t really place where it is coming from (thanks to the obtuse and overly sparse usage of in-world logic).
The store makes the most sense when you realize it’s meant to not give you what you want, so that you buy things “in the mean time, since it’ll disappear soon and then I at least have something” that you would not buy otherwise, getting additional sales out of each person.
Basically if it’s inconvenient that’s the point
And worst is that, what they propose is ugly and even if you had not the recolor/retexture of the first similar cosmetic that was released.
This week, there is nothing I will purchase, cause there is clearly nothing that is worth to buy.