Are just plain ol' boring to me. The last long term dungeon I played was Return to the Temple of Elemental Evil. I couldn't stand having my character stuck in a hole in the ground for the best 8 or so levels of his life, rather than walking around the world, doing his own thing. Granted, I've been called a control freak in RL, and my characters seem to have that trait as well, but to just hang around in a hole in the ground killing shit and taking their stuff ad nauseum is just a waste of time to me.
It's like the difference between the old video game Gauntlet and the newest MMORPG's. The freedom to do what you want to do, and not be tied to a place to go kill shit and take their stuff.
If you like it, more power to you. It's just not to my tastes. I like being above ground, shaping my own character's destiny in the world around him.