Is it?
Heroic dungeons are still spammed even before valor was a thing in wow. Normal was always ran even when pvp offered better rewards.
Honestly the only other content that crashed and burned by not offering extremely powerful rewards for its difficulty was scenarios...
LFR was tested and it was found wanting... I don't even know how you fix it to be honest. If you make it hard it just turns into a three hour wipe a fest till enough raiders que into it to carry it.
LFR has failed at everything it set out to do save to become a loot pinata. At this point it feels like blizzard is giving into the sunk cost fallacy rather then trying to fix it anymore.