The people purchasing tickets for near future cruises know this. At this point with 100% vaxxed what else ya gunna doo? No one setting their hair on fire with someone getting influenza during a trip.
Our family of 4 have already done 36 cruises all over the world, and no one ever got even a cold on any of our cruises. Cruises was our family vacation because it was so much better value than any other vacation. The kids never went to Disney until they were in college and went on their own, once. Now they are 28 & 30 years old, with husbands, and we still do cruises together.