Unfortunately the bar for Casual is on the ground. The easiest way to fix it is to offer good enough rewards to make Ranked worthwhile through the Season. Even just doubling or tripling the tomes and exp from participation would help a bit.

Trying to enforce anything for Casual is sadly a lost cause and waste of resources. It straight up pits top 100 with new players and seems to favor putting them in same team, so playing off Job when there's a decent player or two in opposing team makes it more frustrating than chill experience.

I just try to queue as the same Job as the worst player in my team if I get them few matches in row, but that's always a bit gamble if they swap or you get someone else like them. Safer bet if the queue is fast is to just wait a bit before requeue to get in another match with hopefully fresh player pool.