I once saw another private server implementing a quest chain system award. Finish all the 'find my daughter' related quest in Henesys will unlock some rewards (nothing big, just potions and some extra exp) It's making use of Nexon's existing questlines since who does quests anymore? Even in old maple people are doing pqs (which is why I'm here) and grinding (or socializing exists, thats a thing). A little incentive to do all the quest such as average equips for middle level (40~70) for finishing a big unnecessary quest chain that gives basically nothing for 500 monster drops. Just a little suggestion, I know this will probably take a lot of work and people might not like it cause its not in the original Maple. The server had change many aspect of old Maple for the better, maybe now its time to add some incentives to do all the quests.
In the new source we'll get medals. The quest specialist medal should provide incentive to do quests. Also, I know plenty of people who do quests, simply because they enjoy doing them.