Why are so many people so reluctant to get a passport?
The most recent WHTI regs state that only those passengers arriving by air will be required to have a passport until the "next phase" is implemented.
Stop and think for just a minute folks. WHAT IF in the middle of the caribbean you get really ill and you are taken off the ship for treatment - the ship will sail without you. How do you get home? By air? "May I see your ticket, boarding pass and passport, please? Oh, you don't have a passport? Sorry!" Maybe you charter a plane but when you arrive? "May I see your passport, please? Oh, you don't have one. Please follow me..."
Many (if not all) of the cruise lines have posted on their websites that they will require a valid passport for boarding and will deny boarding without refunds to those not having a valid passport.