I think main point here is that there are generally 2 different motivations for people to run this type of dungeon:
- Player A leveling up the class they are on.
- Player B of higher level running it for the roulette bonus.

Player A probably wants to kill everything and get the chests. Player B just wants to get to the end. I'd regard both as equally "legitimate" and worth respecting. Player A is who it was mostly designed for -- Player B is helping out the less advanced ones. Without Player B you'd probably still be in queue waiting for more people to join group.

Maybe talk about it among the group: The B-type players might be willing to take a bit more time and do the A-type activities if asked. Or they might not. That's their right. Probably just count on getting random mix of both types when you do sub-50 DF dungeons.