I think the nature of the trip and total time away from office comes into to it as well.
When I was still working I would often go into the office in the morning, fly to a European hub mid afternoon, connect to a transatlantic flight to IAD, taxi to hotel. Next morning taxi or metro to meeting, lunch, more meeting, taxi to IAD, transatlantic flight to a Euro hub, connecting flight home, back into office, debrief boss, write a report, home to bed. ZZZzzzz.
I would not do that in Economy. In business I could work westbound and sleep eastbound. If I had to travel in Y I would add at least one night in Washington and I wouldn't be (as) productive westbound.
My time and my comfort is worth the price difference.