We know less about Biannca than we do about the majority of the HMs - I see no reason to write her off as nothing else to offer.
We have 'seen' the other HMs for weeks now, and still we have learnt very little about them: Ash is really only seen as Helen's sidekick, Kim as Steven's doll, Ashleigh in relation to Helen etc etc.
We tend to stop learning anything much new about the HMs as they concentrate on storylines and arguments, but this does not make me believe that all the HMs have nothing else to offer, just that we are not shown the ordinary, everyday things.
Biannca will also have an ordinary, everyday personality that we will not get to know.