Got a couple of questions for you.
As you note, there is a difference between cruise ship hulls and ocean liner hulls. The cruise ship hull being more or less rectangular, and the ocean liner hull being curved from stem to stern and "V" shaped profile when viewed bow-on.
So first question: If ocean liners ply only the Atlantic (a fairly rough patch of water), why would you call for a less stable ocean liner hull? Fuel economy, perhaps -- but at the cost of seasick passengers? A cruise ship hull would seem more suitable.
Second question: Battleship hull design. Every battleship that I'm aware of had an ocean liner type hull. And yet, a battleship is basically a gun platform. And as such, you want the most stable hull design possible. If the ship rocks too much from the recoil of the main battery, precious time is lost until the main battery bears upon the target.
Interestingly, the German battleship Bismarck (and its sister Tirpitz) had ocean liner type hulls, but had a beam of 36 meters! The Bismarck was regarded as one of the most stable battleship gun platforms ever built. But wouldn't it have been even more stable with a cruise ship type hull? Of course it's range would have been reduced, but I suppose everything is a compromise.
Just thought I'd pick your brain a little!