IMHO, airlines are mostly still brands rather than commodities.

The top airlines for service quality - BA, CX, QF, SQ and the like (to take a few at random) - are still strong brands and spend a lot of money investing both in the main brand and the sub-brands of the different classes they offer.

And in most countries, there is still a natural tendency for people of that country to fly "their" airline. So the nationality of the airline is an inevitable part of its branding, however archaic that concept may be.

There are some markets where this is much less marked, of course, and where purchasing is driven much more by pure price. But that's far from universal.