I went on a Caribbean cruise once (the trip was bought for me, I would never have paid for it). The thing I found most striking was the same-ness of every stop. We stopped in Jamaica, but it felt the same as every single other stop: Busy "shopping area" right near the cruise terminal, with many of the exact same stores as the last stop. A variety of the same tired cruise-approved "activities" ("touch a dolphin", "ride a zipline through the forest", "snorkel adventure!") available with just a 1-2 hour cramped bus ride. And, in my experience, not enough time at each stop to actually see much or any of the place we'd landed. The boat stopped in Belize, so I guess I can stick that pin up on my big world-map. Except the "island" we stopped at was wholly-owned by the cruise line and we were only there for four hours, so we mostly gained the experience of buying the same overpriced drinks they had available on the boat, but out of a coconut.

I disagree that cruises are an effective way to visit a place at all, let alone on a low footprint.

in reality is the opposite, the footprint is huge in terms of environmental impact, the cruises pollute the air of the city. Also, cruise visitors use the city's facilities (roads, trash collection, beaches, etc) but don't leave much money behind to compensate. Sure we maximize the amount of people that get to visit the place, but they leave locals worse off as they have to foot the bill