You do have a bit of a point, look at how many models have the same basic face and such because they share a mama who does just variations of one look. It might be cheaper and faster to take that existing model and have it modified than starting from scratch especially with the rigging and toggles already done.The Koinu model could also be altered, recoloured and adjusted before someone debuts it again. That way they'd have a relatively cheap model while still having a "new" VTuber come out of it.
Also, she's not exactly a massive VTubing presence and someone could easily build up a considerable audience even if they alienate a majority of old Koinu followers.