The black hull on the Cunard ships really helps them look better. Its bad enough that the designs of most cruise ships today are hideous, but on top of that you have the bland whitewash color scheme with occasional stripes and such that would look more appropriate on a low-rider in East LA. The Disney ships look especially nice IMO with their twin funnels and black hulls. Nothing beats the classics though.
Yeah, I think it comes from the "every
deck must be a promenade deck" rule for cruise ships, which, well, makes it look like a floating flat building.