The best thing you can pack for a cruise is a big bag of "tolerance". You have expectations of this cruise, but so do others. Use your bag of tolerance as best you can and be tolerant as best you can without getting stressed. But dont waste your vacation because everyone does not think or react like you.
Do your own thing and brush aside some "things" that could potentially bother you, dont let them bother you, enjoy your vacation.
In reality, maybe this packing message is to those that should pack some "consideration" in their cases and then show it when they get onboard to their fellow passengers.
Thats cruising, a big melting pot
and usually the item a lot forget to pack is....consideration