Presumably, the primary reason for this type of system is efficacy, but the patent details some other interesting ways in which a floating blimp full of products might be handy. For one, it could hover above certain large-scale events (think an NFL game or music festivals) and be stocked with goods specifically tailored to the crowd below (merch, snacks, booze, etc.), which individuals could order via their phones. It could also serve as an innovative advertising or marketing tool, flying around at a lower altitude broadcasting a particular product on its exterior, then distributing said product to anyone who's interested down below.
Of course, unleashing this sort of complex aerial system would require a whole lot of approval from aviation authorities, and would likely run up against a bunch of restrictions. And to that end, it's unclear whether Amazon has any intention of legitimately pursuing this in the first place, or is simply hedging its bets for the future. However, considering the company is already actively testing a drone delivery program in the UK, and has successfully revolutionized how the world at large buys and receives its stuff, it may be wise to wait a bit before writing this whole thing off.