We are missing an important part of these dungeons....

It's not all about getting the goodies.

Some of us may actually want to repeat it more often for some legitimate reasons:
1) Fun... we may like doing it!
2) Practice... we may want to get better at doing it, perhaps try it with different jobs.
3) Training.. we may want to take LS mates or other people who have not done it and help them.

I.e: LS Tank has done this many times, and wants to train up a few other LS tanks who have not.. he could do 3-4 runs that nite and teach lots of LS members how to tank and otherwise do the dungeon.

This suggestion would exclude that possibility.

There is more to this world than the shiny stuff hiding in the chest.... especially since it hides so well ^.^;