Japan NEVER used the 2.5 for the WRX/STI. They have always used the EJ20. Now the WRX haves the new engine but STI´s still use EJ207 there. They always keep the good stuff for themselves 

Reading through this thread, I think that you’re looking at this from an American-centric perspective...which if fine - I can safely assume that you’re North American. North Americans like huge cars that are bigger than we need for most circumstances.