Why have trash mobs at all if get no reward if it is a trash and slow you down or like wtf are we doing?, If it give a drop that sucks 99% of the time it will not be worth it. One the things the next generation of the mmos been trying to fix. It one of the reason Free to play games popular. Spend a week. Then the people will just move on to a new game. Hint have a mob kill total kill reward that worth the time on to the boss. When get 90%-100% mob kills. The group get a new rare item for a chance to drop. That is higher then normal stuff. IF get to fancy people just hate it and not have fun.
