Ultimately, everyone figures out that efficiency is the endgame, because the chase goals (completionist, rxp, reaper frags, etc.) are just so horribly grindy that it's only rewarding and satisfying to earn progress at the greatest possible rate.
And the greatest rate is achieved by doing short quests. They give the best xp and rxp/min, and they give the same end chest rewards as long quests for less work
They really need to rebalance longer and older quests to normalize rewards/min, then you'd see more diversity in play again. Better xp, better rxp, and multiple end chests.