Award redeemers aren't just a bunch of leeches though. Many have paid their dues with revenue flights (not all of those seats are credit card mile redeemers). So the airlines do get some value out of the deal.

The Asian carriers that still fly long haul F are largely state owned or have a large state investment anyway. A carrier like TG keeps F as a prestige thing and also for Thai VIPs (royals, government).

But I will agree that the advancements in longhaul C/J class cabins do make F a bit less necessary.