Dungeons would probably feel more epic if the cool monsters with the funky powers were a regular occurrence rather than just bosses.

The add elevator in T7 feels more epic over the course of a few minutes than most entire dungeons do. Even T4, being full of nothing but trash, is more interesting than dungeon fare since you have to pay a tiny bit of attention to positioning, alternate AoE and single target focus, and mind which mobs you are hitting.