In 2008 and 2009, Japan had their qualifiers in autumn 07 / 08 respectively and their national championship was held in early May, so they had an advantage in time of almost 2 months compared to the US. In 2010 they had Nationals in the first week of July, which is almost identical with the date of 2010's US nats (ok, 2 weeks but anyway).
This tricks me into thinking that Pokemon Japan and the PCI want to align their qualifiers and nationals respectively, i.e. want them to be held at approximately the same time.
Furthermore, I believe that Europe could get some kind of European Championships as well, so that you can qualify for the Euro Tournament in several countries, then get to European Championships where you can win the trip to Worlds.