well, the hip area is a famous part of the armor, so, why not? Besides, wouldn't the armour ahve been adapted from protoss? It's kinda hard to adapt armor between two completely different species, and result in it looking different. So, since the hip area is then required to support the rest of the armor (cause the armor is heavy and isn't supposed to crush the shoulders like they otherwise would without the hip area), it is perfectly logical to keep it there, with the second hip area (almost touching the first) clamped around the body.
... Do I need to make a picture of how it would be designed? D: