Roger, I'm sorry to hear you need surgery, and hope all goes well with the healing process.
Regarding cancellation penalties, there's a lot more to a cruise than just a seat from point A to point B. Cruise lines have had this type of cancellation policy for many, many years, and tour companies have similar ones. That is why all decent travel agents urge you to buy travel insurance, to cover you in just such a situation.
By the way, airlines only allow that credit for up to 12 months from the time you bought the ticket, not necessarily 12 months from the time you planned to fly. And you have to pay cancellation/change fees to them as well, usually $100 or so per ticket.