The worst part is that after you complete all the missions once, they become irrelevant, there's absolutely no reason to go back and play them unless they get picked to be the daily heroic. There needs to be some kind of reason to go back and replay those missions. If you could replay each mission once a week on a level close / above your own for an engram + some bonus XP or something that would give people a reason to play what little content outside of the daily / weekly / raid / nightfall more often.