I enjoy the feeling of progression and increasing challenge of fractals, and would like to see that brought over to dungeons to make runs more interesting.
SUGGESTION:
Add levels to dungeon runs like fractals.
Levels are per path, and selected once you select a path.
Increase level like fractals by completing the path.
At levels 10+ agony is introduced like fractals.
30+ you get global challenges like fractals but specific to the dungeon and making things interesting.
This would bring a feeling of progression to dungeons, and provide more challenges, more rewards, and be a blast.