Aram Jabbari explains their decision for the region lock.
"This is NOT the beginning of a new ATLUS policy, nor do we view it as a precedent or a slippery slope," Jabbari said. "If anything, your determination and dedication to what you believe in has certainly stood in the face of that. This is an isolated case, a situation precipitated by a number of factors, some of which are simply out of our North American hands." He admits that Atlus was "completely unprepared for the force with which the community communicated their disapproval."
Jabbari explained that North America and Japanese release will be identical and release quite close in both teriitories, July 26 for Japan and August 7 for North America. "The unforeseen consequence in all of this was that we had a version of our biggest game of the year releasing within a couple weeks in two territories, both identical in content, but at radically different price points."
It seems the reason is so it wont "cannibalize the performance of a title in one territory to the benefit of another." For example the Japanese retail price of Persona 4 Arena is ¥7,329, roughly $92, versus $59.99 in North America.
"The decision to region-lock P4 Arena was a business one, one that has very clearly affected how many perceive the project," Jabbari concluded, "but we ask you to please not overlook the exceptional efforts of the people behind the game and to work with us through constructive dialogue."
It makes sense why the fans are except, this is the first of I heard of a region locked game for PS3, I don't think its worth the negative backlash