The efforts to increase elite rewards over the past few years have had an interesting result, namely that elite has become the default difficulty.
Bravery/Streak bonuses
Because of these bonuses, the loss in XP by running even a single quest on non-elite difficulty is astronomical. Consider that the loss of XP affects not only that quest, but the next five as well while the streak is rebuilt. The result is that nobody runs norm or hard outside of epics. New players' (if there are any anymore) only opportunity to run with vets is to jump straight into elite, a difficulty for which they are likely unprepared.
Loot
Thanks to the above bonuses, there might as well not even be norm/hard versions of heroic named loot. In epics, the existence of EE loot makes elite the default difficulty for all but a handful of quests. Outside of farming for named loot that doesn't have an EE version (i.e., anything from the CitW chain), farming XP for off destinies, and certain raids, running anything but elite is inefficient. The unbalanced drop rate for Commendations of Valor only exacerbates the situation. NOTE: depending on the loot and planned augments, the EH version may be preferable for the lower minimum level. Still, it's kind of akin to having the white bordered version of a M:tG card.
With the current state of difficulty levels, casual, normal, and hard might as well be renamed Casual 1, 2, and 3; because that's how they are viewed. Only the shear difficulty of epic elites keeps normal and hard relevant in epic levels, and I don't think that will last past the end of this year. I think you'll see EE LFMs increasing to the point that normal and hard will disappear from epics, as well.