Cost has a lot to do with it. All 25 of JPs worlds are in one datacenter. That's efficient and cost effective. They get the same thing from the NA datacenter which they went out of their way to put in Montreal rather than Squeenix HQ in California (they bought Eidos) so they were as close to Europe as possible. If they had set up a European datacenter then they would have had to purchase ANOTHER facility and man it and given the current split that would be a datacenter with 7 active worlds...that would probably require almost the same manpower to run as the current 27 world NA datacenter. They obviously decided the investment just wouldn't be worth it simply for the time zone convenience. (Ping issues from Europe to NA should be minimal on a decent ISP unless running content alongside an NA player)