You lock the funds. The thief cannot access them and you will become aware if your funds are in danger. You can postpone the transfer as much as you want until the police can locate the thief. If you cannot locate the thief, you can destroy the funds.
Why destroy the funds? It is the same as death penalty in real life: will deter other people to repeat the crime.
IMO, most bitcoin related thefts are done behind TOR and VPNs that do not keep logs, therefore most thefts are not traceable.
Another issue is that this would lead to additional "transactions" needing to be done by the miners without compensation. In order for this to work properly, both "lock" and "unlock" transactions would need to be confirmed by the miners otherwise the network would not know for sure which one is "correct".
This would also make it much easier to launch what would essentially be double spend attacks against merchants that accept 0/unconfirmed TXs. The attack would work like this: You send a TX to a node that a merchant is connected to, and send a "lock" command to a well connected node a few seconds later. If the "lock" command would have a higher priority then a TX (it would have to in order to be effective) then the "lock" command would take precedent over the TX and the merchant would never receive their funds (having the same effect as a double spend). You would then issue an "unlock" command after the 0/unconfirmed TX is "forgotten" by the nodes
Another issue is that this would make it very easy to attack the network. Someone could easily create thousands of BTC addresses, send a very small amount BTC to each of these addresses and then send "lock" and "unlock" commands for each of these addresses. This would likely overwhelm both the miners and the nodes, making it difficult to even get a TX propagated, or if it is propagated to get it confirmed.