This makes sense, I have a pair of 1:1 bandoleers and I imagine it would be akward to have double pockets that high up. It would hinder other equipment straps, binoculars rifle and like
Mike said it would hinder the mobility with double clips.
And with most of the weight below the center of gravity it makes for a better wear.. I think the designers of these things knew exactly why they where doing it.
Keep your head's down and your helmet's on!