That has been suggested several times already, but I dont really see why its needed - if you want to do those raids and primals properly you're better off without the DF, because as you pointed out correctly:

Quote Originally Posted by Pink2 View Post
3. If there are first timers more than half in the party, it is like unable to clear it. I am ok with trying many times to fail, but most of players don't want it. Some of them just leave after some wipes. (After one leave the duty, none comes for many cases. Then others should leave the duty and queue it for long time again.)
If you want to do them synched, forming a party and learning the fight is the better bet than going through DF, I'd say... a roulette wont change that. The reason the queue-times are so long is indeed because no one does them through DF, but I doubt a roulette would really change that, it would just make it even more frustrating.