Do any ordinary travelers care about the type of plane they're on? Do they even know before they get to the airport? If I had to choose between an old 737 with a 4 hour flight, and an A380 with a 6 hour flight (including the layover) there's just no question. And I can appreciate the presence of a bar in the back! It just doesn't matter that much.

It seems obvious that an airline is going to focus on initial costs, fuel efficiency, customer preferences, etc. And it's not like they don't sell liquor on 737s...