With the way things are now, claims are pretty much pointless because penalty for trespassing is a joke. So I propose a way to make claims a bit scarier - introduce traps that are only placeable on claims.
Specifically, a bear trap that deals a significant amount of damage and keeps the trespasser immobilized for a while. It should also prevent logging out and respawning back at hearth, same how it works when you're in combat. I know that it's damn boring to wait for two hours for your character to free himself (timer going even when you're logged out), but damn it, we need some way to keep those damn kids off our lawns. Make the bear traps require a hefty amount of iron to make, and they won't be spammed left and right.
So, thieving will still be possible, but it will have a high risk to go along with it's high profits. This way people will steal only when they suspect there's something worth stealing, not raid every house they run across.