I've seen a few complaints in regard to people who steal others' loot.
Now I'm not 100% sure what the loot system is like - how it works exactly.
I do however - have a thought.
Remove the 'Master Looter' setting - change it so that if you DON'T want loot, you can set this instead.
If you enter an area and are NOT teamed - loot from YOUR kills is yours, how you define a 'kill' is open to interpretation, whether that's damage, round-robin, who-fired-first, who-killed...
If you enter an area and ARE on a team - loot is round robin.
This way - hopefully, it will stop or severely cut-down on the loot theft, I know how annoying it can be to work on a kill only to find that the loot goes to someone else who sat there and did sweet FA.
Feel free to suggest otherwise or whatever - I'm not pointing fingers - just making an observation and trying to offer a possible solution.