Anyone can fill an aircraft by selling seats cheap enough. But, that's a bad business model. Just ask the carriers who invested in the A380. Need cold hard data to demonstrate that by increasing capacity and adding to the hard & soft product, one can increase PRASM. If it doesn't increase PRASM, it's not worth the extra hot towels.
There is, of course, a luxury market, but history suggests that it is not that large in the leisure sector. The business sector may recover by 2024, but there is a lot of thinking that a good chunk of that is flying Air Zoom for a long time to come.