As far as I can tell the Icon of the Seas is basically fine; even on the environmental front (important!) I see no reason to believe it's worse per passenger than other ships.

A lot of opposition to it feels like elite snobbery against middle / upper-middle-class people.

Any good anti-Icon arguments I'm missing?

As a passenger, I agree. I’ve been on the Allure of the Seas, and although it was almost fully booked, crowd management worked well - Royal Caribbean put a lot of effort into it actually.

But ships of this size are a problem for destinations, which have to handle 6000 visitors at once. That’s 200 excursion buses.

Software developer, founder. Interested in aviation

Which is why cruise lines always visit their “private islands”, basically gated resort communities where they can continue to milk their cash cows. Resembles Disneyworld. Again RCL was a pioneer with their “Labadee”/Haiti property. It’s not everyone’s idea of traveling.

I often get depressed after a few days on such a big ship because everything has to be perfect. Crew is overworked and stressed. Luxury onboard in stark contrast to the outside world. And every imperfection gets amplified in unnatural ways because see above.