Forcing people will never work
You cannot force people to do what they do not want in the game. I stopped doing low level and expert roulette because generally it is a waste of time. I am still doing the high level roulette, but close to stopping doing it too. Many other people do the same, proof is many brayflox 2-3 boss teams in the party finder.
Most of people i meet in DF now are newbies who have recently started playing and would not think of abandoning the dungeon. The harsher penalties are - the less experienced players will queue for roulette, and what can barely geared people do alone?
Today i queued for copperbell in progress for atma book quest - all 3 players were 1st time and stuck at the 2nd boss because had no clue what to do, their healer quit (when i entered they already have been there for 40 minutes). I explained them what to do and we passed the rest of the dungeon in like 15 minutes. I queued for DD (lv44) next and again all 3 players were 1st time, but it is an easy dungeon. I keep getting 3k hp dps and 4k hp tanks for copperbell hard in the high roulette for the 3rd day in a row (i completed those runs but it's an extreme healer task to keep the tank alive).
People leave because they think trying to complete the dungeon is a waste of time.
SE needs to stop being sub-greedy and increase myth/sol rewards in the roulette so doing it will be meaningful again. Any kind of forcing will just make people to stop doing roulettes.