Every bit of content needs a gear cap, i think 840 without titanforging is generous for the easy content, and when a new raid tier comes out, they can increase it further.
You're not supposed to get raid/mythic+ quality loot without putting in the effort.
And sorry, even if there was barely any loot from the world quests, there's other motivations (Rep, AP, order hall resources)
At the end of the day, gear rewards are there for you to progress to the next stage, so world quests only need to reward loot to get you into the next stage which would be actual group content (God i know, grouping in an MMO what's the world coming to)