At that time, the alternatives (767, 747, L1011, DC-10/MD-11...) offered
more space for the passengers.
Today with 10 abreast 777, 9 abreast 787 and A330neo the A321XLR actually offers
wider seats than their widebody competitors, so passengers will love to fly long range in "not that narrow"-body aircraft, which still allows 18 inch wide seats
What still puzzles me is why an 1980s short range aircraft becomes more economic on the transatlantic routes than a 2010s long range aircraft by simply adding additional fuel tanks
Did the modern engineers f*** up the A350/787 design so badly, that an old low sweep all metal wing with a larger engine more disturbing it can beat them ?
If the GTF makes all the difference, why not putting 4 of them on the A340s ? They are available in the required thrust range.