I'm guessing it's mostly cause the model isn't finished or whatever, but it's lacking a lot of detail, particularly in the nose section. It doesn't really feel like the next step up from a Dreadnaught since it shares so many similarities. The change in design for most vanilla ships varies quite a bit from ship class to ship class, particularly in capital ships.
Xing was making super battleship flagships a while back, he did a Rhienland one I know and I'm pretty sure I remember a Liberty one as well. Could be worth looking up, might be floating around on the forums somewhere, most likely in the Media section.