Commercial aviation could stick as many as 850 passengers on an A380-800 in it’s maximum configuration, but the most an airline actually gets is 538 because of business and first class passengers having more room. Increasing passenger space by even 1 inch or just a pound of weight per seat makes a real difference.
Better cupholders do not decrease space at all. Some (better) airlines even have them: they flip down from the seatback. They literally take no space at all. This is ridiculous.