I've been on the Allure of the Seas. The ship's size is over 200 tons and had over 6000 people. The only time it felt crowed was during embarkation because everyone's trying to get on the ship at once. The ship was so big that at times, it felt like we (bf and I) were the only ones in the ship.
I'd go on it again, and if that's someone's definition of hell, then I'll be sure to bring marshmallows, chocolate and crackers for the next trip.
I think you mean 200 THOUSAND tons, 225,000 to be more accurate. And yeah, I've cruised on mega-ships like that, and experienced exactly what you did - virtually no crowds at all. You wonder where everyone is.
My main concern was contagious disease with that many people in a confined space for days, coming from all over the world. But there were automatic hand sanitizers everywhere, which we used, and the crew encouraged other passengers to use them, especially at dining hour, which most seemed to do.
That's a small thing, to be sure, but to my knowledge no one ever got sick. But anyway, I would take exception to the OP's statement that humans are "stuffed" aboard the new cruise ships. I certainly did not experience that on Norwegian Cruise Lines.