How many hours will players grind for a token now worth $15? On the Chinese and European servers — which include Eastern European countries where minimum wages are less than the equivalent of $2 per hour — there are plenty of people willing to sell their time for these prices. There is more of a question of relative value in North America, where players tend to value their time more highly relative to subscription costs.
You should equip new quest rewards when their item level starts beating out your previous set of gear. If you are currently wearing Tier 21 gear, it is best to let the quest rewards significantly beat your existing item level before using them. With that said, you will unlock Azerite pieces early on, which are worth using over Tier gear in most circumstances.