Different tiers of difficulty are not an inherently bad idea but SE refuses to adress the core issue and that is boring job design. The massive gap between normal mode and hard mode is because of this. Jobs are by and large too easy to play so the only way SE has to create difficult encounters is to crank up the encounter difficulty to 11. It's the reason for the excessive body check fights, SE has no other recourse because they refuse the obvious solution: changing their job design philosophy.