Not sure if this was mentioned earlier but from my personal experiences and opinion, LL Roulette is generally a monotonous, dull experience.
A LL Roulette dungeon, is still slower, then any lv50 dungeons. On top of the level sync where you may lose 90% of your abilities. Not very fun for anyone who has been
lv50 for months and months to just sit there spamming 2-3 abilities.

I know personally, I don't bother with them due to the sheer boredom of doing a lv17dungeon as a whitemage. Even with helping on dps, it's still very boring for something that could take me 40-45min on a full clear. Even if they were to up the LL Roulette bonuses or adventurer in need bonuses, it would have to have a very significant incentive to do.