>>89797184NTA but, it's basically just for branding purposes
They want Holos to maintain a specific "look" which includes hair color, Rushia was very lucky she got an outfit that switched her hair from green to pink, approved before management really started to enforce this policy
Around 2022 they expanded this to accessories, stating that make sure that
"unique" aspects of designs don't get infringed upon, so for example a bunch of pre-2022 Holos had cat ears and tail toggles for their outfits, but they don't really allow that anymore (unless it's designed in a way to make a Holo look like she's merely wearing fake car ears rather than them being actually attached to their head) because ideally Cover would like Okayu being "the cat-girl one" unique to her
To related this to Mori, the reason her "bunny girl" outfit is this weird pseudo outfit that sorta looks like a traditional bunny-girl outfit if you squint hard enough is because they had to work around the fact that Pekora is already dressed in one on her default
Kinda dumb, but it is what is