I didn't spot any mention of how the square/cube law favors ever-larger cruise ships. (To a point. Vs. that law is far less friendly to tall buildings, or huge passenger jets, or etc.)

Also, my understanding is that modern cruise ships are built to very low standards for https://en.wikipedia.org/wiki/Seakeeping and resilience. Recall how little damage it took to very quickly sink the https://en.wikipedia.org/wiki/Costa_Concordia_disaster