Maybe just do it for the pre-50 dungeons. Though not sure how it would work. How would the NPC's position themselves or move from AOE's for alot of the dungeons thats critical to staying alive. It's been a little while since I ran low level, but things like if the tank was an NPC. How would they know to pull the boss into the crystal veil, or pull them near pillars? Things like that, I know there are many more positional or AOE events that have to be done properly or expect a wipe.

I guess the only thing would to be reduced damage output from the monsters, but then do the rewards get reduced also unless in a party of players? Seems like the programming behind it would be a bit taxing. It would be neat to have something like a practice mode or something. Something to get in and get the lay of the land. I know most dungeons are pretty linear but I have taken a few wrong turns here and there and got into some trouble.