Well, my thinking is if they are straight out they are in the middle of the range, and it is surely going to be easier to fit clothing to 'em, too. If they are down the sides they have to withstand about 170 degrees of up rotation, that is a awful stretch for thos polygons in the armpit, and a awful compression on those at the top of the shoulder. They will look better on poses near straight down, I agree, but I wonder about bending, and I also wouldn't want to try and make clothing for that position. ;-)