I believe Dazusu is simply saying that having SOME challenges would be nice. Why make alliances 18 people if there is nothing that takes 18 people? Why have 20 jobs when you only really use 4 of them?
I doubt anyone wants to go back to 25k an hour "Awesome exp" or 200 person Day 8 Nidhoggs, but I dont think there is an issue with having to work as a large group to pop and kill an HNM.