The idea why, is this.
- - IF you want to play safe, hunt with no risk of robbing, you can do that in Britannia.
- IF you want bigger loot, you have to enter Sorib Island, where there are no restrictions in looting.
You can enter Sorib Island somewhere between Britian City and Trinsic. There's a portal conjurer, that takes you to a transferring room, where you have to agree on the rules of Sorib Island. After agreeing (basicly to clean looting), you can enter the Island. Sorib Island is packed with the best monsters the shard has to offer and you might even find veins with high value.
Happy hunting,
Boris