Why not construct floating cities? The world is overpopulated (too many people). Thy don't have to pay attention to the hull, just build that block or a floating skyscraper and use tugs to move the whole d*** thing...
I don't see the difference here. Why build larger and larger ships? Theres no meaning anymore to control them with human brain power because in the future you just have one major super-intelligent computer steering the whole ship...
And it's just about design here. This is design meant to take more people, more cabins and more of what you find in a city (bars, disco clubs...spas, fitness, theater).
Soon you will already see cruise ships that got their own opera, major spaces for sport activities etc. It's already on land and it will be a part of the floating giant cruise ships.
I don't see the art in cruise ships. I see modern architecture, but they don't need to put a major hull on them anymore. The art is gone. Now it's just a giant block on the top of the hull structure.