Right now, a smallish number of legendary quests are significantly more popular than others, either due to their ease of completion or their rewards, probably both. We see how making some quests have good reward and time limited (ex. Halloween or Winter events) makes them became popular with the player base. In a similar vein, I suggest that we can select a few quests that are otherwise less popular/rewarding once every few weeks and give them heightened rewards to highlight them and encourage people to play different quests.