Come to think of it, there is a certain logic to a ship design with that much empty space. If the ship is hulled by meteoroids, or by enemy fire, then the more empty space you have, the lower the probability of a populated section being hit. In space, with no air resistance to worry about, there's no cost to having the ship's volume be larger than it has to.
Of course, the empty space would then have to be in vacuum, so that the heat and shock of the impact would not be transmitted to populated sections, and so that no air would be lost from the hull penetration. And that's definitely not what we're seeing in that Adam sketch. Also, it's a moot point when you have magic deflector shields that function as hull armor.