I have not looked at Roxie mesh, but I offer an alternate perspective on what may be the situation.

It is much easier to morph body shapes larger than smaller.

Vic and Dawn start with B/C cup breats and the torso and limbs are shapely.

As raw material for a morph base, I would prefer an A size breast amd baseline limbs and torso.  There should be sufficient verts to support much larger shapes.  The polys should follow and outline the muscle, tendon, ligament, and bone so that they only need inflation and not major lateral moves to get the correct shapes when morphed larger.

  It may be that Roxie was developed with some of these concepts in mind.

Given the nature of the community, such a figure should initially present with a FBM of a more standard body shape so that the community does not reject it.  The base mesh would be morph stock rather than a particularly desirable presentation shape.

The figure would need to have a full raft of body shapes and morphs to begin with, rather than a "here is your base mesh, have at it" approach.