There should be a Daily Dungeon.
Maybe reward can be a random dungeon item.
Theres dailies for pretty much everything but dungeons, and they have been dead for a long time, AND there's no daily for them.
Things need to change.
It does not pop up that often, but it is part of the dailies already. The dungeons do rotate as well, the reward contains 100 dungeon currencies and 1 Tome of Knowledge. Just scroll down the wiki-page.
Strike Missions also have a weekly schedule with a daily recommendation + extra rewards. Same goes for Fractals. Raids however miss this feature entirely. Could be added, either in the way of Dungeons or in the way of Strikemissions/Fractals.
EDIT: That was quick, thanks!