Hey Ruchan!
World quest and emissary rewards are actually intended to be purely for your class, not the talent spec you play on that class. It's always worth pursuing a possible upgrade even for an off-spec in my opinion, but even if it's going to be something you will never use it might count as an average item level upgrade for your character.
Since World Quests and Emissaries scale up their rewards with your average itemlevel, this might mean that when a reward shows up that your main spec could really use, it could be up to an item level 340 item just because you went and collected some good off-spec gear too!