That's because the new J is not design for the narrower Airbus cabin. it is design for the Jumbo and 777, hence you see a big seat loss on the Airbus. If you look at the Jumbo, you will notice that the new layout only has a total of 4 seat loss and 3 of them is in first class and only 1 in J class, with EY stay the same amount of seats. (I pick Jumbo as a comparison because you can not compare the regional 777 to the 77W)