I, to be honest dont understand why they dont just do a world wide release. Let me ask you, if you had the choice, woul you have the game quicker but need to download an update a couple of times or would you rtaher wait a couple of months but need no updates? If it were me i would much much MUCH rather have the game a bit sooner.
Its partly about supply and demand, china has 1.3 billion people, USA has 300 million, If PD does a world wide release the prices for the game would rise instantaneously to $50 USD or higher and it would be harder to find a copy or will take a long time to download the PSN version.