For flights under 4 hours I don’t personally see the bennefit, but the longer you’re in the air the more worth it becomes. On international flights business class can be the difference between being crammed in for 12 hours and being able to lay down like a bed.
It essentially is calling someone a communist supporter. In 1956 Hungry had an uprising against the soviet union (USSR) communist rule. The soviets used tanks to crush the revolutnaries swiftly and used a similar tactic in 1968 to quell similar events in Czechia. When members of the communist party of Great Britain showed support for these actions it became common in GB to refer to them as tankies referencing the attack on hungry. The term has now expanded its use from exclusive to brittish political discourse to more global/universal label for a sympathizer to opressive communist regimes.