Every time I try to take a picture with my phone (Nexus 6), my left hand winds up covering the camera lens, or at least getting close enough to it to interfere. I have to hold the phone awkwardly to shoot the picture. If the camera lens were in the middle of the body, I could comfortably place both hands on the sides and use my thumbs to operate it.
Especially in 6-inch phones like in this case, the cameras could definately be closer to te center than in smaller phones, even with a respectable battery inside. Either by placing the battery on a side a la iphone 6(s) or making it more squarish. The 5.5-inch OnePlus Two managed to place the camera quite nice, and the 3300 mAh battery sits relaxed away from any edge of the chassis...