Its mostly geared toward players that don't have time or teams to do just that. Also, by letting any legendaries get to light 42 they are increasing the amount of useful items, customisation is playing a much larger part now, I haven't used anything bar crota gear and exotics in ages. I imagine the next step, or atleast soon enough, there are going to be more specific rewards for missions, you just have to wait for the item database to expand to accommodate this idea