Another point, related to comments above, is that lawyers and consultants who bill by the hour have very legitimate business reasons to take long flights in biz; any downtime they experience is lost revenue for their firm. Zombie-fy a partner or senior associate for an evening or a whole day upon arrival, or lock them up in a tight Y seat where they don't have enough space to work, and you have lost much more revenue than the marginal cost of a long-haul business class ticket.
I work for an enlightened law firm which pays to put me in business class on long flights, even when the client is only willing to pay for economy (in which case the firm bears the difference). They also expect that I can get some billable work done en route, or go straight to a meeting or take a long conference call upon arrival if needed, which is a fair deal.
Another employer I worked for would usually only fly me long-haul in economy, but left me alone on the day of arrival so I could recuperate as I wished. In the rare cases where they needed me in, say, Tokyo on Tuesday afternoon and then at a 14-hour negotiation session in Dubai first thing Wednesday morning, I could talk them into flying me overnight in business. Also a fair deal.
(FWIW, I feel like I perform better in meetings right after sleeping in J than when I fly in Y and sleep in a hotel bed the night before, but that could just be my natural defense mechanism against crappy flying experiences...)