Scene: the Titanic. It's at the bottom of the sea, hull cracked clean in two.
"The deck chairs are at the back! We need to move them to the front." Racing to the back, he falls into the split, slicing his thigh open on the twisted metal.
"Why is it so hard to breathe down here?" The question is rhetorical. "Capitalism," he burbles. "That's right, it's Capitalism keeping us down! Shipbuilding's dirty carbon! The deck chairs need to be on the left, so we can shut down the dry docks!"
"If you don't like it, go live on the Bismarck," says a third.
Some of the compartments have air trapped in them, but there's whole industries busy stripping the bulkheads for scrap in exactly those areas. Albeit not very effectively, as they can't breathe either.
While it's impressive that any good at all can come from the artificial reef, it's not an argument against having floating ships as opposed to...this.