Here's the thing about Bloomberg's idea to ban sales of large sodas: He's actually acting!
Yes, the ban has holes in it, such as not covering every conceivable high-sugar beverage. And no, if it works to perfection, it will barely dent the obesity problem in only one part of the world. But any sort of success would endorse trying the same or similar measures elsewhere.
Bloomberg sees the same problem we all do, and he's *doing* something, which already has moved more focus to the problem, and to solutions.