ANstar, as you probably already know, galley bulkheads on Airbus types are part of the structural integrity of the aircraft (unlike Boeing). The QF International configured A333's & A332's have larger galleys (than Domestic/JQ) to carry two full service meals and, consequently, there is less floor space available for seats. You're right that they could just replace the seats and accept the reduced capacity but it wouldn't provide the optimum returns required under a LCC model. To modify the galleys to gain the extra seating would be very expensive.