I don't get why the devs choose to do this. More often than not, it ruins the whole chest piece and limits its use for other glamours. If I wanted the lower part too, I'd glamour the legs piece, which is supposed to have that part attached to it instead. Examples of this would be the Riviera dress, the Qitana Ravel set, and the Paglth'an set (I'm sure there are others I'm forgetting). The latter has such a pretty chest part for aiming, scouting, and striking, but the whole thing is ruined because it's attached to the "skirt" thingy (T_T).