Why not make a compromise?

If you sign up for any roulette run, you may also be grouped with people doing the dungeons for story reasons or at least people who have not signed up for a roulette run.

So my proposal is this:
For the expert roulette, we separate the people signing up for roulette and those that didn't. Why? Simple: If SE abandons all those forced stops and mechanics that the OP mentioned (because honestly, I'm starting to hate those, too) in the expert dungeons (or every dungeon that is and will be in the expert roulette), the people doing the expert roulette have the chance to speedrun without forced uncreative hindrances that are boring even if you're doing it the first time. On the other hand, the people who did not sign up for expert roulette, but want to do the dungeon separately/specifically and signed up for that, have the chance to explore and get to know the dungeon, until they feel up to the task of doing the expert roulette