The reason why the Save the Queen areas offer EXP is because Shadowbringers did not get a Deep Dungeon like PotD in HW or HoH in StB, so they allocated resources of what would have been used on the deep dungeon planning, to allow the accumulation of EXP for classes level 71-80.

Keep in mind, Eureka has it's own leveling system, which affects your gameplay and progression in the four areas of Eureka, while Bozja, you only increase your rank which allow use of newer actions.