I think this is related to the level of difficulty of the quest. For example whe you do a quest that you kill opponents that are lvl 12 dont expect the reward to be lvl 14 if you are lvl 14. To me the problem is that you cannot swap characters during the reward screen so you can compare the items with everyone at your party.
Indeed, the difficulty of the combat encounter should be taken into effect, but it's clear that some quests completely ignore that.
I got a quest reward for escorting Sahelia back from the sawmill and learning the third source point. It was level 9. At that point I'm throwing out level 12 stuff as junk.
If the reward was for escorting Sahelia back, that was wrong because the enemies there are level 14.
If the reward was for getting the third source point and maxing out, that was wrong because there is no possible way to complete that quest at level ****ing NINE. At the very least it should be a level 13 reward.
This issue is especially frustrating because of the rapid stat inflation making lower-levelled gear so bad. But I recognize that it's not going to be an easy one to solve.