The blogger writes that development on the XBOX 360 is easier. The developers sign a one year contract of exclusivity with Microsoft and the company provides developers with the funding to create the project. The blogger also mentions that Microsoft's support team is very thorough.
So with a low cost, funded and well supported XBOX 360 "exclusive" shipped and out of the door, developers have a core game. Which one year later (when the contract of exclusivity expires) they can then port to the Playstation 3; which in the case of these Japanese-centric titles, is where the bulk of the return is made.
The reason many new features are added to the Playstation 3 versions of these ports is because Sony won't license a title that's exactly the same. Thus the PS3 version tends to see a host of exclusive content.