This "issue" is completely overblown. Statics don't have this problem as they can easily pre-determine who gets what. 95% of the "I got ninja'ed" claims come from someone whining about losing some loot they never had a right to in the first place. This would get abused way too much. Need/greed isn't abused, either it is your class or it isn't. I always love that guy who doesn't get the roll for his job, then after the fight is over "Hey, I play that class too, plz greed"

The system isn't broke, high level groups can already implement this. If you can't trust the whole group, what makes you so sure you can trust the "leader"?