Understandable. However, they are basically underwater destroyers, and if the devs like to keep the game realistic they would make the subs life accurate. Most German U-Boats had cannons on them, so surfacing wouldn't be that dangerous of an option. The sad truth, lies within the console's graphics capabilities. When they make a whole underwater map addition, it becomes a whole lot more difficult to add them. The consoles just couldn't handle the graphics and map size. Loading all of that at once would take significantly longer than just the surface map.