Doc, this is one of the very rare occasions when I am going to disagree with you.
If you are a very small person (as I am), running the straps the usual way can end up with them chewing holes in the inside of your upper arms, and having the webbing sit on the ball of your humerus (the bumpy part of the shoulder) rather than in the natural channel just inside of it (where a purse strap would sit). Crossing the straps brings them closer in to the body, and relieves that problem. I used to finish my dives with ugly linear bruises on my upper arm -- no more.
The cost is that it lowers the backplate about an inch or so, which is not an issue unless you are diving doubles AND find that you can't set the tanks high enough, which is rarely a problem. The other issue I've run into is that some drysuits are cut so that the latex neck seal runs low enough to have the straps chafe on it. I solve that by having the shop put a warm neck collar on the suit, but if that hadn't been an option, I was going to get some neoprene to put on the straps where they cross.