Any increased penalty to leaving would just make people abuse afk or forced d/c to get kicked to get out of the group instead anyway. Personally I'm in favor of anyone who bails on a group within the first 15 minutes loses the roulette bonus for that day. Any group that still struggles after that point is most likely going to vote abandon anyway or they would have made it far enough that taking an additional 30 minute penalty would take longer than sticking it out.