This is not a new idea. There are several different concepts published on making a self-sufficient society capable of living on water or in the event of a cataclysmic event. One went so far as to detail how it could technically become its own country (and get a seat in the UN).
I say this will gain traction when the zombie apocalypse begins. =P
it's never been an good idea, it's posible to sink , if there to many they would disturb export/inports , than on what kind of moter because of the world ... etc etc
I can just speak 4 myself but when im on a oil rig for 2 weeks or more. You get pretty dam tired of being sorounded by water then theres the hygene factor. Disease spreads alot faster on boats and oil rigs, since you are all crammed together on a small area. And then there is the seasickness ive been on boats where at least half of the crew is laying all over the boat and puking. Luckily i dont get seasick myself.