Yeah, I'd like to see them add other duties to this, similar to how Trial roulette works. I think they have refrained, because in their minds it's the best way to ensure that people will participate and help newbies with Castrum Meridianum and Praetorium, cause let's face it, outside of friendship and the roulette exp bonus, there's very little reason to do those dungeons.

Quick note though about Leveling roulette: It doesn't involve any 8 man duties. Only 4 man duties, with story mode trials < lvl 50 included, as it used to be called, "Low Level Roulette." But what you're getting at is correct, they can literally put any duty that is linked to the DF into a roulette.