I now only do Low Level Duties for leveling...Or rather, I would, if it didn't take more then 90 minutes for a party to form... (Both of my healer class/jobs are leveled and I don't want to touch tanks yet.)
Players who aren't leveling have no incentive to join the Low Level Duties, ST gives far better rewards (Tomes, Oil, Sand, iLevel 100 gear, even a derp minion) and takes less time (and compared to some fights/dungeons, the fight mechanics are easier).