It's downstream of a bunch of retail game shops - GameStop, Newegg, Toys'R'Us, RadioShack - all going tits up over the last ten years. Giving up on physical media isn't some Machiavellian business play. It's a response to their historical vendors dying out.

Unless Sony starts opening up their own mall kiosks, they won't have anywhere to sell physical copies outside Amazon or Walmart. And there's a reason you don't want these two to be your primary retail pipeline.