EXACTLY! For a phone that's already being sold in Europe, has a better processor, better version of TouchWiz, better version of android, nfc (in some cases) and a couple other plusses, AT&T seems to be SERIOUSLY gimping their android offerings.
Its like the Infuse.... almost identical phone to the EVO... only no FF Camera, and smaller battery... oh.. and a YEAR LATER!
It probably costs less for AT&T. Besides, Android OS currently has no use for the extra core. So it will be as fast as the dual core Galaxy S2 as far as CPU goes. Dual core phones are purely a bragging right right now until Google figures out how to migrate HoneyComb Dual-core support down to Android OS.