Not all TK's cut their cod. Only a vocal few of them that thinks it's the holy grail of trooping comfort. Aside from the accuracy standpoint, you won't be going to the bathroom as often as you'd imagine while trooping. Most of your fluids leave your body as sweat, just like in sports. But also, don't go to the bathroom in armour. It's not very hygienic, and kind of gross. Kids will be playing with your armour, and you don't want pee all over it.
It's also partly because of the way you cut your cod that's the problem. Yes, it's a clever solution, but the angled cuts show up a lot more than just a straight horizontal cut across the cod would have, which is easily hidden by the belt.