I'm not sure about this... Maybe I just don't like the idea of losing items, but I'm not into the whole thievery thing. At least it's extremly good on making me paranoid while walking around in spawn xD
On the other hand, it's pretty much useless in PvP-zones (why steal when you can kill?).
Oh and about opening blocked chests (not LWCs); I think you could add more to that skill. What if it could be used for something better? I'm thinking about a skill that could allow you, for a very small amount of time, to be able to destroy/add blocks within town-regions (not personal-regions though, would be too OP at spawn). All the blocks that were destroyed/added would be changed back once the skill ends (making it pretty much impossible to use for griefing) and of course, the skills would need mastery and have an expensive reagent and a long CD.
Of course, it seems a bit OP, so more restrictions should probably be made. The thing is (some people will probably disagree with me on this one), it should be possible to at least add some threat to the more well-secured towns. As of now, the only thing raiders can do is to stand outside of the town's gate and taunt the inhabitants or possible grind players that didn't get time to take cover. Maybe in the future there could be a war-system, allowing towns to fight and enter each other's regions